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 21 for “"cavity geometry"”.
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Study of Thermochemical Non-equilibrium and Sensor Cavity Geometry in Hypersonic Flow
… flat plate with a flush-mounted sensor, an open cavity with a length-to-depth ratio of 2, and a closed cavity with a length-to-depth ratio of 16. The data demonstrate that the flat plate configuration has the best optical performance and that the closed cavity has the worst. Additionally, the …
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Study of Cavity Geometry to Improve Optical Quality of Windows in Hypersonic Flow
The optical quality of the window-air system of a flight vehicle in hypersonic flow is simulated. The optical distortion of the window-air system is the metric of merit. Within the earth’s atmosphere, vehicles at hypersonic speeds may generate viscous and high-temperature thermal boundary layers. …
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Internal Fluid Dynamics and Frequency Characteristics of Feedback-Free Fluidic Oscillators
… properties such as the working fluid, scale and cavity geometry of the fluidic oscillator. Non-dimensional parameters were defined by taking the effects of these variables into account to allow effective comparison of fluidic oscillator designs. Furthermore, 33 modified designs were also tested …
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Investigation of the Effects of an Upstream Cavity on the Secondary Flow in Transonic Turbine Blade Passages with Endwall Contouring
… with respect to the presence of an upstream cavity that approximates the gap present in actual engines between the rotor and stator of an HP turbine. Further, it aims to assess the viability of using non-axisymmetric endwall contouring to reduce endwall losses, including those generated by …
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Optical and Thermal Analysis of a Heteroconical Tubular Cavity Solar Receiver
… and optimise the Heteroconical Tubular Cavity receiver for a parabolic trough reflector. This study presents a three-stage development process which allowed for the development, investigation and optimisation of the Heteroconical receiver. The first stage of development focused on the …
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Development of detectors for the monitoring of mixed radiation fields
… project. The detector features a microstructured geometry with deep cavities filled with neutron converter materials, designed to enhance neutron capture efficiency while maintaining compatibility with pixelated readout electronics. A comprehensive simulation framework combining GEANT4, TCAD …
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Computational Modelling and Experimental Verifcation of Quasioptical Components at Millimetre Wavelengths
… of the modes present in the resonant Fabry-Perot cavity. Detailed analysis was performed using CST, a full electromagnetic modelling package on resonant metallic cavities related to describing a waveguide coupled bolometer for the SAFARI instrument on the proposed SPICA space telescope mission. A …
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Incompressible flow over a three-dimensional cavity
… flow passing over a three-dimensional cavity on a solid surface. This study has been divided into two parts: 1) incompressible laminar flow passing over a three-dimensional cavity; and 2) incompressible laminar-to-turbulent transition over a three-dimensional cavity.<br/><br/>In the …
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HEAT TRANSFER IN SQUEEZE CASTING OF LIGHT ALLOYS
… the pressure distribution in the die cavity during squeeze casting of magnesium alloy AM50. This experiment aimed to reveal the changes of pressure distribution with the cavity geometry as well as the local cavity pressure at various locations during the solidification process. To …
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Laser-induced plasmas in air for pulsed broadband cavity-enhanced absorption spectroscopy
… inside a high-finesse near-concentric optical cavity. The broadband optical plasma emission was successfully sustained within the cavity and the light leaking from the cavity was used to measure broadband absorption spectra of gaseous azulene through (i) time-dependent cavity ring-down (CRDS), …
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THz polaritonics : control, confinement, and strong light-matter interactions
… Our experiments, performed in both waveguide and cavity geometries, conclusively proved the formation of new quasiparticles we termed magnon-phonon-polaritons. We believe our results open up the possibility of using polaritonics for facile and coherent ultrafast control and conversion between …
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Hot embossing of polymeric tubular micro-components
… of two categories: the first category was Geometry Factors, which include the die-cavity geometry and tube inner/outer diameter ratio; the second category was Process Parameters, which include the forming temperature, maximum applied force, embossing velocity and dwelling time. The samples …
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Unsteady aerodynamics using high-order methods
… To gain more insight into the topology of 3D cavity flows, an experimental study using non-intrusive measurement techniques is outlined. This explains the work performed on 3D cavities with different spanwise dimensions. A detailed flow visualisation of the meanflow patterns in various …
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Ultrafast terahertz spectroscopy and control of collective modes in semiconductors
… in InSb by means of a plasmonic one dimensional cavity. By control of the cavity geometry, we shifted the plasmon mode into the regime where non-local electron-electron interaction is enforced. We observed the consequential Landau damping of the collective mode, in good agreement with the …
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Numerical Modeling of Synthetic Jets in Quiescent Air with Moving Boundary Conditions
… jets in quiescent air to study the influence of cavity geometry and boundary conditions of the piezoelectric diaphragm on jet velocity. Numerical simulation is performed for two synthetic jet cavities of different height and orifice diameter. The numerical modeling utilizes a turbulent RNG κ – ε …
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Experimental Design and Analysis of Piezoelectric Synthetic Jets in Quiescent Air
… performance gains. These devices consist of a cavity with an oscillating diaphragm that divides it, into active and passive sides. The active side has a small opening where a jet is formed, whereas and the passive side does not directly participate in the fluidic jet.Research has shown that the …
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Fluctuation-induced interactions and nonlinear nanophotonics
… of the thesis focuses on the study of various geometry-enabled resonant effects leading to strong nonlinear interactions. The starting point of this work is a coupled-mode theory framework for modeling a wide range of resonant nonlinear frequency-conversion processes in general geometries, …
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Photonic integrated circuit for the manipulation of coherent optical combs
… of input signals. By using more complicated cavity geometry devices such as distributed feedback (DFB) and sampled grating distributed Bragg gratings (SG-DBR) narrowband filtering is achievable with high suppression (>30 dB) of spurious wavelengths. The active nature of the devices also means …
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A combined cycle approach to dual-mode scramjet design and analysis
… of the axisymmetric isolator-combustor geometry for the newly developed flowpath was conducted as a direct-connect configuration in the ACT-II arc-heated hypersonic wind tunnel. It was revealed that at the ground test conditions the current geometry struggled to achieve the expected …
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TIME DOMAIN CHARACTERIZATION OF MONOLITHIC QUANTUM DOT PASSIVELY MODE-LOCKED LASERS
… regions of mode-locking stability for a given cavity geometry, are derived from measurements of modal gain and absorption on a multi-section single pass emitter. The effects of temperature on the operational range of pulses emitted from the quantum dot ground and excited states are …
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