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 19 of 19 for “"High angular resolution"”.
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High Angular Resolution Beam Steering Terahertz Antenna Arrays for Imaging Applications
… of antennas, a fraction of the size required for high-resolution imaging. This is explained by challenges including THz phase shifters which are high-loss and too large for dense integration, consume large DC power, and introduce amplitude and phase errors. In addition, challenges exist with …
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Localization and Lensing of Fast Radio Bursts using CHIME/FRB and its VLBI Outriggers
… detects about 700 FRBs per year, but lacks the resolution to pinpoint its bursts. Very-long baseline interferometry (VLBI) is a solution which uses widely-separated telescopes to achieve high angular resolution, but this technique has been limited to following up the small fraction of sources …
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Novel Phantoms and Post-Processing For Diffusion Spectrum Imaging
<p>High Angular Resolution Diffusion Imaging (HARDI) techniques, including Diffusion Spectrum Imaging (DSI), have been proposed to resolve crossing and other complex fiber architecture in the human brain white matter. In these methods, directional information of diffusion is inferred from the peaks …
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Mass Functions and Mass Segregation in Young Starburst Clusters
… is resolved in unprecedented detail with high angular resolution, near-infrared instruments. In the case of the Arches cluster, diffraction-limited, adaptive optics observations are analysed, and the achievements and limitations of ground-based vs. space-based diffraction-limited imaging …
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High-Resolution Characterization of Micro-Scale Crack Tip Fields in Zirconium
… in the future. In this dissertation, two high-resolution experimental techniques, high (angular) resolution electron backscatter diffraction (HR-EBSD) and high (spatial) resolution digital image correlation (HR-DIC), are used in combination with crystal plasticity-based finite element …
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Ultrafast laser fabrication of a K-band integrated optic 2-telescope beam combiner for astronomical interferometry
… existing JouFLU beam combiner at the Center for High Angular Resolution Astronomy (CHARA) array. A liquid crystal on silicon phase-only spatial light modulator (SLM) is integrated into a conventional ULI fabrication system to control the laser phase profile at the objective plane. During the …
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Shadows, Mirrors, and Snow: Decoding Multibounce Light Transport in Time-of-Flight Photography
… of lidar with the wide field of view and high angular resolution of photography. The result of this combination is that time-of-flight cameras by nature capture videos of light as it flows through the photographed scene. Unlike regular photographs, time-of-flight photographs expose the …
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One-Dimensional MEMS Optical Phased Array Systems Based on Surface Micro-Machined Silicon Mirrors for Scanning LiDAR Applications
… moving parts, leading to a fast response, high reliability, and low power requirements. MEMS based OPA systems generally demand narrow and tightly spaced suspended microstructures with high-aspect-ratios in the lateral dimensions, rendering some significant challenges in the system design, …
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High-Resolution Imaging of Dense Gas Structure and Kinematics in Nearby Molecular Clouds with the CARMA Large Area Star Formation Survey
… is limited by existing data that do not combine angular resolution needed to resolve individual cores with area coverage required to capture entire star-forming regions and with tracers that can resolve gas motions. The original contributions of this thesis to astrophysical research are the …
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Understanding star formation at early stages in the filamentary era
… in massive starless cores, our results from high angular resolution observations with CS(2-1) using CARMA show three to five fragments associated with each core, in a broad consistency with the models involving turbulent fragmentation. The number of fragments suggest that magnetic fields may …
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Studies of solar white-light flares and small-scale magnetic structures observed in the near infrared
… non-existence of "dark faculae". Several high-resolution observations have been carried out at BBSO and National Solar Observatory/Sacramento Peak. The data benefited from a newly developed state-of-the-art near-infrared photometric system and the high-order adaptive optics system. In …
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High Resolution Continuous Active Sonar
… work presented focuses on methods for achieving high range, Doppler, and angular resolution, while maintaining a high signal-to-interference plus noise ratio (SINR).</p><p>CAS systems transmit at or near 100\% duty cycle for improved update rates compared to pulsed systems. For this reason, CAS …
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Connecting models and observations of disc evolution and planet formation
… and aims to assess what mechanism, turbulent angular momentum transport or angular momentum removal by magneto-hydrodynamic winds, drives disc evolution. This is a long-standing issue with crucial consequences for many aspects of planet formation, from dust growth, pebble and gas accretion on …
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Synthesis Imaging with Vector Sensor Arrays
… would need to be impractically large to obtain high angular resolution at frequencies below roughly 100 MHz. Instead, to observe frequencies between 10 MHz and 100 MHz, observatories use interferometric arrays of electrically-small antennas such as dipoles. At even lower frequencies, below about …
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Disconnected interferometry at 81.5 MHz
… is a well established technique that enables high angular resolution measurements to be made with a radio interferometer containing independent local oscillators and signal recorders. This Thesis addresses the problems encountered when this technique is applied to low frequency (81.5 MHz) …
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The formation of high-mass stars and stellar clusters in the extreme environment of the Central Molecular Zone
… early precursors to young massive clusters and high-mass proto-stars, with a specific focus on the extreme environment in the inner few hundred parsecs of the Milky Way -- the Central Molecular Zone (CMZ). The primary sources of interest that are studied in detail belong to the Galactic centre …
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The Galactic Starburst Region NGC 3603 : exciting new insights on the formation of high mass stars
… research is addressed by the question "How do high mass stars form?". While most details related to the formation and early evolution of low mass stars are quite well understood today, the basic processes leading to the formation of high mass stars still remain a mystery. There is no doubt that …
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Spatial Audio for Bat Biosonar
… spatial audio decoding technique called HARPEx (High Angular Resolution Planewave Expansion) was used to build a system providing angle and elevation estimates. HARPEx can estimate the direction of arrivals (DOA) for up to two simultaneous sources since it decomposes a signal into two dominant …