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 12 of 12 for “"Velocity Change"”.
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An Ultrasonic Study of Trapped Hydrogen Tunneling Systems in Niobium and Tantalum
… frequencies between 10 MHz and 55 MHz. The sound velocity change due to H in Nb was measured in both the normal and superconducting state at 10.8 MHz and 33 MHz at temperatures between 0.5 K and 18 K. The attenuation and velocity change due to trapped D in Nb was measured in both the …
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An ultrasonic study of trapped hydrogen tunneling systems in Nb and Ta
… frequencies between 10 MHz and 55 MHz. The sound velocity change due to H in Nb was measured in both the normal and superconducting state at 10.8 MHz and 33 MHz at temperatures between 0.5 K and 18 K. The attenuation and velocity change due to trapped D in Nb was measured in both the …
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Propagation of zero sound in liquid He3
… of 15.4 MHz and was 19.3m K for 45.5 MHz. The velocity of the sound was found to be relatively temperature independent at high and low temperatures but near the attenuation maximum the velocity changed by 3.5 ± 0.3 percent. The results of the measurements are predicted by the Landau theory of a …
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Analytical methods for satellite constellation reconfiguration and reconnaissance using low-thrust manoeuvres
… overight by more than 85%, for less than 20 m/s velocity change, when compared with a non-manoeuvring satellite. The second scenario considers a constellation of 24 satellites that can manoeuvre to provide targeted coverage of a region of the Earth as required. A full set of manoeuvres for all …
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Utilizing Changes in Repeating Earthquakes to Monitor Evolving Processes and Structure Before and During Volcanic Eruptions
… The behavior of repeating earthquakes sometimes changes with time, which possibly reflects subtle changes in the mechanism creating the earthquakes. In Chapter 1, we document an example of repeating earthquakes during the 2009 eruption of Redoubt volcano that became increasingly frequent with …
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Passive Seismic Tomography and Seismicity Hazard Analysis in Deep Underground Mines
… of tomographic imaging survey. An initial velocity model is established according to properties of a rock mass, then velocity structure is reconstructed by velocity inversion to reflect the anomalies of the rock mass. Mining-induced seismicity and double-difference tomographic images of …
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Investigation of Linear and Nonlinear Torsional Guided Waves in Hollow Circular Cylinders for Damage Detection
… studies are carried out to observe the group velocity change with respect to different levels of loading. The nonlinear features, such as combinational harmonics and second harmonics, are also investigated numerically and experimentally.
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Debris collision avoidance maneuver optimization (CAMO) for satellite constellations
… minimize collision probability (Pc) and total velocity change (∆V ). A high-fidelity simulation environment was constructed in MATLAB, incorporating J2-perturbed dynamics for debris and Keplerian propagation for satellites to capture realistic relative motion and nodal drift. The Probability of …
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Study of reactive flow, ground deformation and real-time tomography with applications on CO₂ sequestration
… defer global warming and avoid dangerous climate change. Carbon dioxide is also injected into reservoirs to increase resource extraction. Currently, the rate of CO₂ injection in pilot sequestration plants or the enhanced oil recovery commercial projects is a few million tons CO₂ per year at best, …
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Imaging the D" Structure using Waveform Modelling
… The top of D'' region characterises a velocity discontinuity - the D'' discontinuity, which likely originates from the phase transition from bridgmanite (Bm) to post-perovskite (pPv) at the pressure-temperature conditions of the lowermost mantle. This discontinuity has been widely …
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Imaging the D" Structure using Waveform Modelling
… The top of D'' region characterises a velocity discontinuity - the D'' discontinuity, which likely originates from the phase transition from bridgmanite (Bm) to post-perovskite (pPv) at the pressure-temperature conditions of the lowermost mantle. This discontinuity has been widely …
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Single-crystal elasticity of Al-rich phases in the Earth’s transition zone and lower mantle
… build mineral models that describe the seismic velocity and density of different rock lithologies within the transition zone and lower mantle. Single-crystal elastic properties of two majoritic garnets (Mg3.24Al1.53Si3.23O12 and Mg3.01Fe0.17Al1.68Si3.15O12), synthesized at 1900 °C and 17 GPa, …