The goal of the research was to develop best practices for image signal processing method for InSAS systems for bathymetric height determination. Improvements over existing techniques comes from the fusion of Chirp-Scaling a phase preserving beamforming techniques to form a SAS image, an interferometric Vernier method to unwrap the phase; and confirming the direction of arrival with the MUltiple SIgnal Channel (MUSIC) estimation technique. The fusion of Chirp-Scaling, Vernier, and MUSIC lead to the stability in the bathymetric height measurement, and improvements in resolution. This method is computationally faster, and used less memory then existing techniques.

Este trabalho apresenta o projeto e desenvolvimento de dois sistemas de calibração de acelerômetros. O primeiro sistema foi desenvolvido a partir de um sistema interferométrico laser Hewlett-Packard (HP 5529A), utilizado como padrão de referência absoluta. Este sistema foi projetado com o propósito de calibrar acelerômetros-padrão de comparação e acelerômetros-padrão de transferência. O segundo sistema de calibração utiliza como padrão de referência acelerômetros-padrão de comparação. Este segundo sistema foi projetado com o objetivo de calibrar acelerômetros de uso corriqueiro. Desta forma, o conjunto formado pelos dois sistemas de calibração podem ser rastreáveis até os padrões primários, nacionais e internacionais. Para cada um dos sistemas de calibração são apresentadas discussões relativas às suas características construtivas, aos testes de operação e às avaliações sobre os desempenhos alcançados. / This work presents the design and development of two accelerometer calibration systems. The first system was developed from a Hewlett-Packard laser interferometric system (HP 5529A), taken as an absolute reference standard. This system was designed to allow calibration of comparison standard accelerometers and transfer standard accelerometers. The second calibration system, which employs comparison standard accelerometers as reference, was designed to calibrate common use accelerometers. Thus, the arrangement of the two calibration systems can be traceable until the primary national and international standards. For each calibration system, a discussion is presented, concerning their constructive characteristics, operation testing and evaluation of accomplished performance.

Interferometric Synthetic Aperture Radar (InSAR) is an established technique which has been applied to Earth surface displacement analysis and topographic reconstruction. Two complex coherent SAR acquisitions of the same scene are combined to form an interferogram from which surface displacement or terrain measurements are made. The similarities between both SAR signals is captured in the coherence and its magnitude is determined by the spatial separation between acquiring antennas and the changes (if any) to the physical characteristics of the scattering target in the duration between both SAR acquisitions. Both of these products derivable from the interferometric process have been applied in this study with the aim of enhancing monitoring and assessing changes in the coastal environment, with emphasis on the coastal geomorphology. A combination of remote sensing data acquired for Montrose Bay, NE Scotland, has been used to analyze changes to the geomorphology of the beach and dune system in terms of sediment volume analysis, erosion and accretion processes and shoreline changes over a short-term period of 4 years. The interferometric coherence was applied to detect changes to the dune morphology, which have been actively eroding at the southern flank of the Bay. The interferometric analysis presented in this thesis was based on SAR data acquired by the Sentinel-1 SAR antenna and the results demonstrated the limitations of the sensor for terrain mapping and DEM reconstruction. In addition, the significance of the vegetation on the interferometric coherence was demonstrated. However, the results have shown that temporal baseline remained a significant consideration in the application of interferometric coherence in highly dynamic environments such as the coastal environment.

Este trabalho apresenta o projeto e desenvolvimento de dois sistemas de calibração de acelerômetros. O primeiro sistema foi desenvolvido a partir de um sistema interferométrico laser Hewlett-Packard (HP 5529A), utilizado como padrão de referência absoluta. Este sistema foi projetado com o propósito de calibrar acelerômetros-padrão de comparação e acelerômetros-padrão de transferência. O segundo sistema de calibração utiliza como padrão de referência acelerômetros-padrão de comparação. Este segundo sistema foi projetado com o objetivo de calibrar acelerômetros de uso corriqueiro. Desta forma, o conjunto formado pelos dois sistemas de calibração podem ser rastreáveis até os padrões primários, nacionais e internacionais. Para cada um dos sistemas de calibração são apresentadas discussões relativas às suas características construtivas, aos testes de operação e às avaliações sobre os desempenhos alcançados. / This work presents the design and development of two accelerometer calibration systems. The first system was developed from a Hewlett-Packard laser interferometric system (HP 5529A), taken as an absolute reference standard. This system was designed to allow calibration of comparison standard accelerometers and transfer standard accelerometers. The second calibration system, which employs comparison standard accelerometers as reference, was designed to calibrate common use accelerometers. Thus, the arrangement of the two calibration systems can be traceable until the primary national and international standards. For each calibration system, a discussion is presented, concerning their constructive characteristics, operation testing and evaluation of accomplished performance.

We report the results of high-angular-resolution observations that search for exozodiacal light in a sample of main sequence stars and sub-giants. Using the "jouvence" of the fiber linked unit for optical recombination (JouFLU) at the center for high angular resolution astronomy (CHARA) telescope array, we have observed a total of 44 stars. Out of the 44 stars, 33 are new stars added to the initial, previously published survey of 42 stars performed at CHARA with the fiber linked unit for optical recombination (FLUOR). Since the start of the survey extension, we have detected a K-band circumstellar excess for six new stars at the similar to 1% level or higher, four of which are known or candidate binaries, and two for which the excess could be attributed to exozodiacal dust. We have also performed follow-up observations of 11 of the stars observed in the previously published survey and found generally consistent results. We do however detect a significantly larger excess on three of these follow-up targets: Altair, v And and kappa CrB. Interestingly, the last two are known exoplanet host stars. We perform a statistical analysis of the JouFLU and FLUOR samples combined, which yields an overall exozodi detection rate of 21.7(-4.1)(+5.7) %. We also find that the K-band excess in FGK-type stars correlates with the existence of an outer reservoir of cold (less than or similar to 100 K) dust at the 99% confidence level, while the same cannot be said for A-type stars.

We present new spatially resolved observations of MWC 349A from the Large Binocular Telescope Interferometer (LBTI), a 23 m baseline interferometer made up of two, co-mounted 8 m telescopes. MWC 349A is a B[e] star with an unknown evolutionary state. Proposed scenarios range from a young stellar object, to a B[e] supergiant, to a tight binary system. Radio continuum and recombination line observations of this source revealed a sub-arcsecond bipolar outflow surrounding an similar to 100 mas circumstellar disk. Follow-up infrared studies detected the disk, and suggested that it may have skew and an inner clearing. Our new infrared interferometric observations, which have more than twice the resolution of previously published data sets, support the presence of both skew and a compact infrared excess. They rule out inner clearings with radii greater than similar to 14 mas. We show the improvements in disk parameter constraints provided by LBTI, and discuss the inferred disk parameters in the context of the posited evolutionary states for MWC 349A.

Limb darkening is a fundamental ingredient for interpreting observations of planetary transits, eclipsing binaries, optical/infrared interferometry and microlensing events. However, this modeling traditionally represents limb darkening by a simple law having one or two coefficients that have been derived from plane-parallel model stellar atmospheres, which has been done by many researchers. More recently, researchers have gone beyond plane-parallel models and considered other geometries. We previously studied the limb-darkening coefficients from spherically symmetric and plane-parallel model stellar atmospheres for cool giant and supergiant stars, and in this investigation we apply the same techniques to FGK dwarf stars. We present limb-darkening coefficients, gravity-darkening coefficients and interferometric angular diameter corrections from Atlas and SAtlas model stellar atmospheres. We find that sphericity is important even for dwarf model atmospheres, leading to significant differences in the predicted coefficients.

Limb darkening is a fundamental ingredient for interpreting observations of planetary transits, eclipsing binaries, optical/infrared interferometry and microlensing events. However, this modeling traditionally represents limb darkening by a simple law having one or two coefficients that have been derived from plane-parallel model stellar atmospheres, which has been done by many researchers. More recently, researchers have gone beyond plane-parallel models and considered other geometries. We previously studied the limb-darkening coefficients from spherically symmetric and plane-parallel model stellar atmospheres for cool giant and supergiant stars, and in this investigation we apply the same techniques to FGK dwarf stars. We present limb-darkening coefficients, gravity-darkening coefficients and interferometric angular diameter corrections from Atlas and SAtlas model stellar atmospheres. We find that sphericity is important even for dwarf model atmospheres, leading to significant differences in the predicted coefficients.

The astronomical size of spectral data cubes that will result from the SKA pathfinders planned large HI surveys such as LADUMA; Fornax HI survey; DINGO; WALLABY; etc. necessitate fully automated three-dimensional (3D) source finding and parametrization tools. A fraction of the percentage difference in the performance of these automated tools corresponds to a significant number of galaxies being detected or undetected. Failure or success to resolve satellites around big spirals will affect both the low and the high mass end of the HI mass function. As a result, the performance and efficiency of these automated tools are of great importance, especially in the epoch of big data. Here I present the comprehensive comparison of performance between the fully automated source identification and parametrization software: SOFIA, the visual galaxy identification method and the semi-automated galaxy identification method. Each galaxy identification method has been applied to the same ∼ 35 gigabytes 3D HI data cube. The data cube results from the blind HI imaging survey conducted using the Westerbork Synthesis Radio Telescope (WSRT). The survey mapped the overdensity corresponding to the Perseus-Pisces Supercluster filament crossing the Zone-of-Avoidance (ZoA), at (`, b) ≈ (160◦ , 0.5◦ ). A total of 211 galaxies detected using the semi-automated method by Ramatsoku et al. [2016]. In this work, I detected 194 galaxies (using the visual identification method) of which 89.7% (174) have cross-matches/counterparts on the galaxy catalogue produced through semi-automated identification method. A total of 130 detections were made using SOFIA of which 89 were also identified by the two other methods. I used the sample of 174 visual detections with semi-automated counterparts as a Testbed to calculate the reliability and completeness achieved by SOFIA. The achieved reliability is ∼ 0.68 whereas completeness is ∼ 0.51. Further parameter fine-tuning is necessary to have a better handle on all SOFIA parameters and achieve higher reliability and completeness values.

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