Dissertations / Theses: 'Astrophysics and Space Science'

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Bonokwane, Kelebogile. "SALT and TESS monitoring of central stars of planetary nebulae." Master's thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33436.

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Planetary Nebulae (PNe) are the product of Asymptotic Giant Branch (AGB) evolution. Evolved from Solar-like intermediate mass stars (0.8 – 8M), they have a hot, radiating core that ionizes the gas of the expelled envelope, producing a glowing nebula. The core eventually evolves into a white dwarf (WD), following the WD cooling track. Complex, aspherical morphologies are observed in PNe and binary central stars (CSs) have been the favoured explanation for deviations from spherical symmetry. Finding and characterizing the population of binary CSs is thus important to understand the physics behind their morphologies. The objects of this study are Hen3-1333, Hen2-113 and Hen2-47, all with WolfRayet (WR) CSs that commonly exhibit fast, dense stellar winds. All exhibit multipolarity in their young nebulae, Hen3-1333 has a disk and dual-dust chemistry, while the other two have central stars offset from the geometric centre of their nebulae. The objects were chosen because most of these features, especially multipolar morphologies, are not well represented amongst PNe with known binary CSs. Here we develop a quantitative time-series analysis to determine whether these objects have binary CSs and develop constraints to permissible orbital parameters. The High Resolution Spectrograph (HRS) of the Southern African Large Telescope (SALT) was used to collect échelle spectroscopic data over 3 years and The Exoplanet Survey Satellite (TESS) was used to obtain photometric data for the objects. The medium resolution (MR) mode (R ≈ 40000) was chosen and 58, 60, and 35 spectra were collected for Hen3-1333, Hen2-113 and Hen2-47, respectively, with an average S/N of 40 at 4495 Å. The TESS data had continuous sampling (30 min cadence) recorded for an orbit length of 27.4 days. Using cross-correlation and Gaussian line fitting, radial velocity (RV) time-series were compared to lightcurves determined from the TESS data. Lomb-Scargle periodograms were used to search for periodic variability in the RV and photometry time-series data. The results were discussed based on short (0 – 10 days), intermediate (10 – 103 days) and long (103 – 104 days) orbital period ranges. Compatible scenarios for each range were estimated by combining observational constraints with different parameters expected for assumed companion star types. The quantitative variability analysis excludes short orbital period binary systems, suggesting that if their multiple features are due to binary interactions, the most likely case is the long orbital period range. If the variability observed is due to a companion, rather than pulsations from the CS, the companion masses, 0.10 – 1.36 M for Hen3-1333, 0.043 – 1.27 M for Hen2-113 and 0.077 – 1.36 M for Hen2-47, correspond to main sequence stars and dwarfs.

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Oreta, Timothy. "Vector-Galileon-Tensor theories of gravity." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20925.

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A detailed study of the cosmological evolution in a particular vector-tensor theory of gravity with a potential and a Galileon-motivated interaction terms is presented. The evolution of vector field self interactions that are relatively related to Galileon fields throughout the expansion history of the universe is considered and a classification of the parameters M (mass term) and H (Hubble parameter) according to the behaviour of the field in each cosmological epoch is carried out. In particular, we obtain conditions for the parameters so that the field grows exponentially or oscillates with decreasing amplitude. We also obtain an autonomous system for the inflationary case. The general features of the phasemaps are given and the critical point is appropriately characterised. It is not possible to obtain an autonomous system for radiation and matter dominated epochs hence, we consider other analytical methods. We obtain eigenvalues and hence, phasemaps. The general features of the phasemaps are given and the point to which the trajectories on the phasemaps converge is appropriately characterised. Therefore, we show that it is possible to obtain a wide variety of behaviours or interesting phenomenologies for the cosmological evolution of vector field self-interactions that are relatively related to Galileon fields by choosing suitable values for the parameters M and H of given conditions.

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Misra, Anuj. "Towards a holographic description of pulsar glitch mechanism." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15589.

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This work aims to review the progress in understanding the underlining physics of pulsar glitches: beginning from the pedagogical development of the subject to eventually motivating the use of AdS/CFT techniques in studying a certain class of condensed matter systems. The foundation of this work is built upon the Gross Pitaevskii (GP) model of super-fluidity applied to the interior matter of neutron stars, where the condensate wave function acts as the order parameter of the macroscopic coherence theory. The excitation modes of the field equations are found to be solitonic vortices, which then go on to present a theoretical basis to the plausible theories of pulsar glitches involving vortex dynamics. The second major thrust of this thesis is in reviewing the application of AdS/CFT in study of strongly-coupled condensed matter systems, with special attention to the models of holographic superfluidity that admit vortex-like solutions. The basic identification of the characteristic free energy configuration of global vortices in the AdS/CFT prescription enables to motivate its use in studying the pulsar glitch mechanism. The last part of this work traces the conclusions of this review and attempts to present the current state-of-progress of the field with its extensive domain of purview and open lines of inquiry.

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Kubwimana, Jean Claude. "Cosmic acceleration and the coincidence problem." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/6102.

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Includes abstract.
Includes bibliographical references (leaves 83-89).
In the standard model of the Universe, the cosmos has only accelerated once since decoupling and only recently, at around a redshift of z ̃ 0.5 as supported by different observations including Type Ia Supernovae (SNIa), the Cosmic Microwave Background (CMB), Large Scale Structure (LSS), and Weak Lensing (WL). This confirmation however, lacks a fundamental physics explanation. The hypothetical form of energy termed 'dark energy' (DE) assumed to account for that acceleration behavior, is still mysterious and why its dominance only occurred recently is a profound problem widely known as the coincidence problem. So far all attempts for resolving the coincidence the problem have been unsatisfactory. Here we investigate a possible solution to the coincidence problem in the form of multiples phases of acceleration (MPA). If there were more than one phase of acceleration between now and decoupling, then the current phase of acceleration would be much less special, alleviating the coincidence problem. We use a modified Markov Chain Monte Carlo (MCMC) technique together with the WMAP five year TT data to search for parameters allowing a second phase of acceleration. Despite extensive search we find no models that simultaneously fit the WMAP data and yield a second phase of acceleration, ruling out this particular set of models as the solution to the coincidence problem.

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Obonyo, Willice Odhiambo. "Open clusters and HII regions of our Galaxy." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/19997.

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Open clusters are essential laboratories for understanding stellar evolution, as they allow constraints to be placed on stellar ages and luminosities. As distance indicators they are also important tracers of star formation in the Milky Way. One such cluster is Trumpler 27 that we identified for detailed study.The aim of the study is to estimate the distance, radial velocity, age, membership and reddening of the cluster using both spectroscopic and photometric techniques. We used new spectroscopic data collected from SAAO's 1.9m telescope together with existing photometric data from catalogues in the study of Trumpler 27. The spectra collected were classified using spectral atlases to determine the reddening in the field. Stars of the cluster were identified using selection techniques that made use of both infrared and optical Q parameters, spatial distribution and photometric techniques. The result from this work suggest that Trumpler 27 is made up of ~ 55 stars which are at different stages of evolution. The stars include main sequence stars, blue supergiants, two cool supergiants and maybe two WR stars.

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Tapsoba, Wendyam Blaise. "Analysis of SALT Fabry-Pérot medium resolution data." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16494.

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The Southern African Large Telescope Fabry-Pérot interferometer has been used in its medium resolution mode to observe three of 30 galaxies of the MHONGOOSE galaxy sample for which very deep HI observation (typically 200 hours/galaxy) will be obtained with MeerKAT. So optical high spatial resolution of 2 arcsec data of NGC 7361, NGC 7424 and NGC 7793 have been obtained. The major object of this thesis was to test SALT Fabry-Pérot medium resolution data in order to pursue the survey of all the MHONGOOSE sample, and to be able to compare the accuracy of the kinematic results. Through this work, some FORTRAN based routines have been improved and they allow us to compute kinematic maps with good accuracy. Indeed, the velocities measured from the profiles of the Hα emission in the data cube are accurate with the range of 1 km s⁻¹ to 10 km s⁻¹. So, we computed the kinematic maps and the rotation curves of the three galaxies using DiskFit and ROTCUR. For NGC 7361 and NGC 7424 we compared the rotation curves derived by both methods. For NGC 7793 we were also able to compare our results with previous studies.

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Tshenye, Thapelo Obed. "Quality control of astronomical CCD observations." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/4409.

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Okouma, Patrice M. "Type Ia supernovae as tools for cosmology." Master's thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/4424.

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Sikhonde, Muzikayise E. "A study of chameleon-photon mixing from pulsars." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12638.

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Includes bibliographical references.
A number of solutions to the dark energy problem have been proposed in literature, the simplest is the cosmological constant A. The cosmological constant lacks theoretical explanation for its extremely small value, thus dark energy is more generally modelled as a quintessence scalar field rolling down a flat potential.

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Affadi, Ikechukwu Patrick. "A new method of mapping cosmic flow fields : evaluating the sustainability of the infrared bands Tully-Fisher relation for ZoA work." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20813.

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This thesis aims at using the Infrared Survey Facility (IRSF) JHKₛ bands, Two Micron All Sky Survey (2MASS) JHKₛ bands and Wide Field Infrared Survey Explorer (WISE) W1-W4 bands isophotal magnitudes to understand the cosmic flow associated with Zone of Avoidance (ZoA) galaxies.

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Hlabathe, Michael. "Post-common-envelope binary central stars of Planetary Nebulae in the OGLE-IV survey." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20870.

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Planetary Nebulae (PNe) are defined as the ionized shells of circumstellar gas ejected through an intense stellar wind at the end of the star's life. PNe come in different shapes, from spherical to highly complex, non-spherical shapes. Mass loss in AGB stars is presumed as the shaping mechanism but how it results in different PNe morphologies is still unclear. Binary central stars that have undergone common envelope evolution are thought to be a possible solution to this longstanding problem. Using photometry from the OGLEIV survey, we present the newly identified close binary central stars of Planetary Nebulae (CSPNe), six in total. Of the six PNe with close binary CSPNe, one looks spherical which presents a very interesting argument in terms of our understanding of PNe evolution. The orbital distribution is derived and compared against current orbital distribution for binary CSPNe, with most binaries from the distribution exhibiting orbital periods less than a day. A binary fraction estimate of 6% is presented and possible cases are discussed that might have influenced our estimation to be different from the expected 10-15%.

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Sorgho, Amidou. "Observing galaxies in the Southern Filament of the Virgo Cluster with KAT-7 and WSRT." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16495.

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To date, our understanding of the formation and evolution of galaxies attributes a very important role to the neutral hydrogen (HI) gas since it constitutes the reservoir of fuel out of which galaxies form stars. In their evolution, galaxies interact with each other and with their environment, and very often these interactions leave fingerprints in the HI distribution. The extended HI envelopes of galaxies are sensitive tracers of those tidal interactions. In the present study, we map the HI distribution of galaxies in a ~1.5° X 2.5° region of the Virgo cluster using the Karoo Array Telescope (KAT-7) and the Westerbork Synthesis Radio Telescope (WSRT). With a total observing time of ~78 hours with the KAT-7 and 48 hours with the WSRT, we search for low HI column density features in the region. Despite the different observing time and beam size of the two telescopes, we reach similar column density sensitivities of NHI ~1 X 10¹⁸ atoms cm⁻² over 16.5kms⁻¹. With a new approach, we combine the two observations to map both the large and small scale structures. We detect, out to an unprecedented extent, an HI tail of ~60 kpc being stripped off NGC 4424, a peculiar spiral galaxy. The properties of the galaxy, together with the shape of the tail, suggests that NGC 4424 is a post-merger galaxy undergoing a ram pressure stripping as it falls into the centre of the Virgo Cluster along a filamentary structure. We also give the HI parameters of the galaxies detected.

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Hodges, Andrew. "The everyday geopolitics of science in post-Yugoslav space : from war and 'transition' to economic crisis." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/the-everyday-geopolitics-of-science-in-postyugoslav-space-from-war-and-transition-to-economic-crisis(498797c2-d703-44da-b979-0eaf33107cf0).html.

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My research concerns how the changing geopolitical positioning of the post-Yugoslav states has impacted on the lives and prospects of students and researchers in the natural sciences. The main focus is on scientists’ experiences and self-reporting, both of the situation at present and during the nineties, when scientific operations and scientists’ lives were disrupted by war and in the case of Belgrade, Serbia, UN sanctions against science. My fieldwork is centred on participant ethnography based at an institute in Belgrade, Serbia (the Belgrade Astronomical Observatory). However, throughout the thesis I trace and make connections between numerous other institutes and networks, as well as drawing on interview material and ethnography completed with students in Belgrade and Zagreb, Croatia. I analyse in particular on the impact of the recent wars, attempted ‘democratic transition’ and the current European economic crisis. My main argument is that whilst neoliberalisation and social changes over the past forty years have created opportunities for scientists globally, these opportunities were not evenly distributed. For scientists committed to living and working in the former Yugoslav region, these changes were often, but not always experienced as a hindrance; particularly as seen through the lens of reperipheralisation, which strongly relates to the context of war and recent scientific isolation. In the introduction and first chapter of the thesis, I detail the background in light of which ethnographic insights in the later chapters make sense. I then examine how scientists’ practices and experiences reflect, relate to, shape and have been shaped by not only post-Yugoslav discursive hegemonies (chapter two), but also disciplinary changes (chapter three), local academic hierarchies and conventions (chapter four), the socialist legacy and attempted neoliberal ‘transition’ (chapters two, three, four and five), academic traditions (chapter six) and national cosmology (chapters two and six). The thesis also attempts to make an original contribution to anthropological studies of science, in particular engaging with Latour and Woolgar’s (1986) work on credibility (chapter three), literature on science and its publics (chapter five) and the historiography of science (chapter six). The thesis also draws heavily on anthropological theory from other traditions in the discipline, including Marxist anthropology and theories of hegemony (chapter two), Bourdieu’s (1984) work on education (chapters two and four), Verdery’s (1995) analysis of cultural politics under socialism (chapters three and five) and exchange theory, including Graeber’s (2011) work on debts and indebtedness (chapter six). One key theoretical claim advanced through the ethnographic material is that an anthropological study working with scientists in what Blagojević (2010) terms the ‘semiperiphery’, and where a series of violent wars had recently took place, warrants a human focus, namely on the scientists and how they collectively dealt with and coped with disruption to their work and the reorganisation of their social worlds.

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Ignace, Richard. "Astro4U: An Introduction to the Science of the Cosmos." Digital Commons @ East Tennessee State University, 2014. http://amzn.com/1634870697.

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Astro maths -- The sky -- Astronomy of the ancients -- Renaissance astronomy -- The astronomer's toolbox: physical principles -- Overview of the solar system -- The sun, our nearest star -- Earth, the home world -- The moon -- The terrestrial planets -- The gas giant planets -- The dwarf planets -- Major moons of the solar system -- Solar system debris -- Properties of the stars -- The formation of stars -- The lives of stars -- Stellar corpses -- The interstellar medium -- Living in a galaxy called the milky way -- Galaxies -- Active galaxies and quasars -- Cosmology -- Exoplanets -- The search for life. The book Astro4U: An Introduction to the Science of the Cosmos excites students about the grandeur of astronomy and how the universe functions. Filled with vibrant figures and informative tables that support the written text, the book has a fresh, casual, student-friendly tone that dramatically increases interest in the material while also making it more accessible. The book provides a college-level description of science with astronomy serving as the vehicle of delivery for displaying the scientific model. The content follows a traditional progression of scale, beginning with a study of the sky, followed by discussions of ancient and medieval astronomy, modern scientific practices, and key physical principles. Chapters move through the Solar System, stars, then galaxies, and finally the cosmos as a whole. Additionally, the book presents astronomy as the story of light and gravity, crucial threads that permeate the text. Because students often express concern about the math content in astronomy classes, the book begins with a chapter entitled "Astro Maths" that reviews all the mathematical skills and concepts needed to complete the course. This up-front investment increases student confidence, eliminates one of the primary blocks students face, and improves chances for student achievement and success. Astro4U is written for general education survey courses in astronomy that are geared to non-science majors.
https://dc.etsu.edu/etsu_books/1016/thumbnail.jpg

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Moore, Christopher Samuel. "Atomic Layer Deposition Re ective Coatings for future Astronomical Space Telescopes and the Solar Corona viewed through the MinXSS (Miniature X-ray Solar Spectrometer) CubeSats." Thesis, University of Colorado at Boulder, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10680697.

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Advances in technology and instrumentation open new windows for observing astrophysical objects. The first half of my dissertation involves the development of atomic layer deposition (ALD) coatings to create high reflectivity UV mirrors for future satellite astronomical telescopes. Aluminum (Al) has intrinsic reflectance greater than 80% from 90 ? 2,000 nm, but develops a native aluminum oxide (Al2O3) layer upon exposure to air that readily absorbs light below 250 nm. Thus, Al based UV mirrors must be protected by a transmissive overcoat. Traditionally, metal-fluoride overcoats such as MgF2 and LiF are used to mitigate oxidation but with caveats. We utilize a new metal fluoride (AlF3) to protect Al mirrors deposited by ALD. ALD allows for precise thickness control, conformal and near stoichiometric thin films. We prove that depositing ultra-thin (~3 nm) ALD ALF3 to protect Al mirrors after removing the native oxide layer via atomic layer etching (ALE) enhances the reflectance near 90 nm from ~5% to ~30%. X-ray detector technology with high readout rates are necessary for the relatively bright Sun, particularly during large flares. The hot plasma in the solar corona generates X-rays, which yield information on the physical conditions of the plasma. The second half of my dissertation includes detector testing, characterization and solar science with the Miniature X-ray Solar Spectrometer (MinXSS) CubeSats. The MinXSS CubeSats employ Silicon Drift Diode (SDD) detectors called X123, which generate full sun spectrally resolved (~0.15 FWHM at 5.9 keV) measurements of the sparsely measured, 0.5 ? 12 keV range. The absolute radiometric calibration of the MinXSS instrument suite was performed at the National Institute for Standards and Technology (NIST) Synchrotron Ultraviolet Radiation Facility (SURF) and spectral resolution determined from radioactive sources. I used MinXSS along with data from the Geostationary Operational Environmental Satellites (GOES), Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), Hinode X-ray Telescope (XRT), Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) and Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) to study the solar corona. This resulted in new insights on the coronal temperature distribution and elemental abundance variations for quiescence, active regions and during solar flares.

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Wegryn, Eric. "The dusty atmosphere of Mars: A study of the properties of martian aerosol dust, using Imager for Mars Pathfinder and Hubble Space Telescope observations." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/289700.

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The properties of aerosol dust on Mars may be deduced from photometric observations of its atmosphere. By comparing sky images taken by the Imager for Mars Pathfinder to numerical models, the size distribution and reflective properties of the dust particles can be determined. The format, quality, and reduction of the IMP images is described herein, as is the computational radiative transfer model used, with its various parameters. After discovering and compensating for an imprecision in the pointing of the camera, models were successfully fit to the IMP solar aureole datasets. Key results include determining the particle size (reff = 1.6 ± 0.15 μm); quadratic parameters G and Θmin describing the phase function for internally scattered light as functions of wavelength; and the imaginary refractive index n i (and single scattering albedo o) of the aerosols as a function of wavelength (presented in Table 4.1). Preliminary indications of temporal variation in ni turn out to be due to an unplanned change in the time of day of the measurements, coupled with a limitation in the algorithm for correcting the aforementioned pointing imprecision. Excluding unreliable datasets leads to a set of particle properties which shows no significant variation over the first two months of the Pathfinder mission. A multispectral sky patch from MPF Sol 22 gives greater wavelength resolution, as well as showing the sensitivity of the results to variations in key model parameters. In addition, images from the Hubble Space Telescope are used to refine the surface reflectance used in the model. The final result is a model for the aerosol dust which is consistent with the IMP solar aureole observations and the HST observations. Evidence for a minor component of water ice is also discussed. Dust reflectances derived for comparison with ground spectra show a feature in the near infrared which is not present in most MPF spectra of bright surface regolith. This is an indication that there are components visible in the bright soil which are not present in the airborne dust.

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Tatum, Brian Shane. "Rearranging an Infinite Universe: Literary Misprision and Manipulations of Space and Time, 1750-1850." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1404533/.

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This project explores the intersection of literature and science from the mid-eighteenth century to the mid-nineteenth century in the context of this shift in conceptions of space and time. Confronted with the rapid and immense expansion of space and time, eighteenth and nineteenth-century philosophers and authors sought to locate humans' relative position in the vast void. Furthermore, their attempts to spatially and temporally map the universe led to changes in perceptions of the relationship between the exterior world and the interior self. In this dissertation I focus on a few important textual monuments that serve as landmarks on this journey. During the eighteenth and nineteenth centuries, the intersection of literary and scientific texts transformed perceptions of space and time. These transformations then led to further advancements in the way scientific knowledge was articulated. Imagination became central to scientific writing at the same time it came to dominate literary writing. My project explores these intersecting influences among literature, astronomy, cosmology, and geology, on the perceptions of expanding space and time.

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Pourbaix, Dimitri. "Space astrometry of unresolved binaries: from Hipparcos to Gaia." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210649.

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Building upon its success with the Hipparcos space astrometry mission launched in 1989, the European Space Agency has agreed to fund the construction of its successor, Gaia, and its launch in 2011. Despite the similarities between the two missions, Gaia will be orders of magnitude more powerful, more sensitive, but also more complex in terms of data processing. Growing from 120,000 stars with Hipparcos to about 120,000E4 stars with Gaia does not simply mean pushing the computing resources to their limits (1 second of processing per star yields 38 years for the whole Gaia-sky). It also means facing situations that did not occur with Hipparcos either by luck or because those cases were carefully removed from the Hipparcos Input Catalogue.

This manuscript illustrates how some chunks of the foreseen Gaia data reduction pipeline can be trained and assessed using the Hipparcos observations. This is especially true for unresolved binaries because they pop up so far down in the Gaia pipeline that, by the time they get there, there is essentially no difference between Hipparcos and Gaia data. Only the number of such binaries is different, going from two thousand to ten million.

Although the computing time clearly becomes an issue, one cannot sacrifice the robustness and correctness of the reduction pipeline for the sake of speed. However, owing to the requirement that everything must be Gaia-based (no help from ground-based results), the very robustness of the reduction has to be assessed as well. For instance, the underlying assumptions of some statistical tests used to assess the quality of the fits used in the Hipparcos pipeline might no longer hold with Gaia. That may not affect the fit itself but rather the quality indicators usually accompanying those fits. For the final catalogue to be a success, these issues must be addressed as soon as possible.

Agrégation de l'enseignement supérieur, Orientation sciences
info:eu-repo/semantics/nonPublished

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Petiteau, Antoine. "DE LA SIMULATION DE LISA A L'ANALYSE DES DONNEES. Détection d'ondes gravitationnelles par interférométrie spatiale (LISA : Laser Interferometer Space Antenna)." Phd thesis, Université Paris-Diderot - Paris VII, 2008. http://tel.archives-ouvertes.fr/tel-00383222.

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Les ondes gravitationnelles sont émises par une large gamme de sources astrophysiques et cosmologiques. L'étude des ondes à basse fréquence telles que celles émises par les binaires de trous noirs, les EMRIs ou encore les fonds galactique et stochastique, nécessite l'utilisation d'un détecteur spatial. C'est la mission LISA (Laser Interferometer Space Antenna) composée de trois satellites distants de 5 millions de kilomètres et qui s'échangent des faisceaux lasers afin de former plusieurs interféromètres. La bonne compréhension de ce projet complexe nécessite le développement d'un simulateur tel que celui réalisé pendant cette thèse, LISACode. C'est un simulateur scientifique de LISA qui s'attache à rester au plus proche de la réalité du détecteur, sans pour autant le décrire au niveau des détails d'ingénierie. Il fournit des flux de données similaires à ceux de la future mission et applique la méthode TDI qui réduit effectivement le bruit laser. Ainsi il permet de tester des points technologiques importants de LISA et de mener des études scientifiques sur les ondes gravitationnelles. C'est un outil essentiel pour la préparation de l'analyse de données qui est un point capital de la mission LISA. Ainsi le second point de cette thèse porte sur le développement d'une méthode d'analyse basée sur l'étude de la modulation d'amplitude du signal gravitationnel induite par le mouvement LISA. Cette étude donne accès à la position de la source. L'application de cette méthode a nécessité la mise en place de méthodes d'extraction du signal. Les résultats obtenus pour une onde monochromatique et pour une onde émise par une binaire de trous noirs super-massifs sont prometteurs.

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Parent, Damien. "Observations de pulsars avec le Fermi Gamma-ray Space Telescope." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2009. http://tel.archives-ouvertes.fr/tel-00461405.

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Le Large Area Telescope à bord du satellite Fermi, lancé le 11 juin 2008, est un télescope spatial observant l'univers des hautes énergies. L'instrument couvre l'intervalle en énergie de 20MeV à 300 GeV avec une sensibilité nettement améliorée et la capacité de localiser des sources ponctuelles. Il détecte les photons gamma par leur conversion en paire électron-positron, et mesure leur direction et leur énergie grâce à un trajectographe et un calorimètre. Cette thèse présente les courbes de lumières et les mesures spectrales résolues en phase des pulsars radio et gamma détectés par le LAT. La mesure des paramètres spectraux (flux, indice spectral, et énergie de coupure) dépend des fonctions de réponse de l'instrument (IRFs). Une méthode développée pour la validation en orbite de la surface ecace est présentée en utilisant le pulsar de Vela. Les efficacités des coupures entre les données du LAT et les données simulées sont comparées à chaque niveau de la rejection du fond. Les résultats de cette analyse sont propagés vers les IRFs pour évaluer les systématiques des mesures spectrales. La dernière partie de cette thèse présente les découvertes de nouveaux pulsars individuels tels que PSR J0205+6449, J2229+6114, et J1048-5832 à partir des données du LAT et des éphémérides radio et X. Des analyses temporelles et spectrales sont investies dans le but de contraindre les modèles d'émission gamma. Finalement, nous discutons les propriétés d'une large population de pulsars gamma détectés par le LAT, incluant les pulsars normaux et les pulsars milliseconde.

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Eyring, Nicholas J. "Development and Validation of an Automated Directivity Acquisition System Used in the Acquisition, Processing, and Presentation of the Acoustic Far-Field Directivity of Musical Instruments in an Anechoic Space." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4004.

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A high spatial resolution acoustic directivity acquisition system (ADAS) has been developed to acquire anechoic measurements of the far field radiation of musical instruments that are either remote controlled or played by musicians. Building upon work performed by the BYU Acoustic Research Group in the characterization of loudspeaker directivity, one can rotate a musical instrument with sequential azimuthal angle increments under a fixed semicircular array of microphones while recording repeated notes or sequences of notes. This results in highly detailed and instructive directivity data presented in the form of high-resolution balloon plots. The directivity data and corresponding balloon plots may be shown to vary as functions of time or frequency. This thesis outlines the development of a prototype ADAS and its application to different sources including loudspeakers, a concert grand piano, trombone, flute, and violin. The development of a method of compensating for variations in the played amplitude at subsequent measurement positions using a near-field reference microphone and Frequency Response Functions (FRF) is presented along with the results of its experimental validation. This validation involves a loudspeaker, with known directivity, to simulate a live musician. It radiates both idealized signals and anechoic recordings of musical instruments with random variations in amplitude. The concept of coherence balloon maps and surface averaged coherence are introduced as tools to establish directivity confidence. The method of creating composite directivities for musical instruments is also introduced. A composite directivity comes from combining the directivities of all played partials to approximate what the equivalent directivity from a musical instrument would be if full spectral excitation could be used. The composite directivities are derived from an iterative averaging process that uses coherence as an inclusion criterion. Sample directivity results and discussions of experimental considerations of the piano, trombone, flute, and violin are presented. The research conducted is preliminary and will be further developed by future students to expand and refine the methods presented here.

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Civet, François. "Caractérisation de la structure électrique interne de Mars par méthode d'induction électromagnétique à partir des données magnétiques satellitaires de Mars Global Surveyor." Phd thesis, Université de Bretagne occidentale - Brest, 2012. http://tel.archives-ouvertes.fr/tel-00740386.

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Les méthodes d'induction électromagnétique permettent de caractériser la conductivité électrique des matériaux, dont les corps planétaires telluriques, depuis les couches superficielles de la croûte jusqu'aux zones les plus internes, dans le manteau inférieur. Pour une source de champ électromagnétique donnée, des courants sont induits dans les matériaux qui y sont soumis. Avec l'essor des données magnétiques satellitaires, de nouvelles méthodes d'analyse des données magnétiques permettent d'obtenir des image unidimensionnelles de la structure électrique de ces corps car la structure spatio-temporelle de la source électromagnétique en est bien connue. Les travaux de mon doctorat ont eu pour but de mettre en place une nouvelle méthode d'analyse permettant de déterminer des modèles de structure interne globaux pour n'importe quel corps du système solaire pour lequel on dispose de longues séries temporelles magnétiques satellitaires. Après avoir testé cette méthode sur des modèles synthétiques et l'avoir appliqué au cas de données réelles terrestre pour lesquelles des études d'induction électromagnétiques antérieurs permettent d'avoir un a priori sur le modèle de conductivité électrique attendu, nous avons obtenu les premiers modèles de conductivité électrique martien en utilisant les données magnétiques du satellite Mars Global Surveyor. Ces résultats nous ont permis de valider des modèles de structure interne antérieurs établis à partir d'analyses géochimiques et minéralogiques des météorites martiennes. Cette méthode innovante est aujourd'hui la seule capable d'obtenir une image électrique des manteaux telluriques à partir de données magnétiques satellitaires pour des corps autres que la Terre ou la Lune et pour lesquels aucun a priori sur la structure spatio-temporelles du champ électromagnétique inducteur externe n'est nécessaire.

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Billot, Nicolas. "Etalonnage d'un nouveau type de détecteur bolométrique pour l'instrument PACS de l'Observatoire Spatial Herschel." Phd thesis, Université Paris Sud - Paris XI, 2007. http://tel.archives-ouvertes.fr/tel-00292030.

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La mission Herschel est un des projets phare du programme scientifique de l'agence spatiale européenne (ESA). Son objectif est d'explorer le ciel dans l'une des régions du spectre électromagnétique les moins connues à ce jour : l'infrarouge lointain. Sa résolution, sa sensibilité mais aussi son domaine spectral font de Herschel un observatoire unique et parfaitement adapté à l'étude des mécanismes de formation d'étoiles et d'évolution des galaxies. Parmi les autres thµemes scientifiques qui bénéficieront des observations Herschel se trouvent les noyaux actifs de galaxie, les disques circumstellaires ou encore les comµetes de notre systµeme solaire.
De nombreux instituts de recherche ont participé à l'élaboration de ce projet ambitieux, notamment le CEA qui a développé un nouveau type de détecteur bolométrique pour le photomµetre de l'instrument Herschel/PACS.
Ce manuscrit rend compte du travail de recherche que j'ai effectué au Service d'Astrophysique du CEA dans le cadre de ma thµese de doctorat. Ma tâche a consisté d'une part à développer une procédure de caractérisation adaptée aux nouvelles matrices de bolomµetres du CEA, et d'autre part à réaliser l'étalonnage du photomµetre PACS et à optimiser ses performances dans les différents modes d'observation ouverts à la communauté astronomique.
Dans ce manuscrit, je présenterai les grandes lignes de l'astronomie infrarouge de la découverte du rayonnement infrarouge par William Herschel à la réalisation de l'Observatoire Spatial Herschel. Je décrirai également les développements d'hier et d'aujourd'hui dans le domaine de la bolométrie refroidie afin de mettre en perspective les innovations apportées par le CEA, à savoir la fabrication collective de bolomµetres, la thermométrie haute impédance, le multiplexage à froid et l'absorption du rayonnement par cavité résonante. J'exposerai ensuite le principe de fonctionnement des matrices de bolomµetres, étape nécessaire pour comprendre la problématique de la procédure de caractérisation que nous avons mise au point. Puis je présenterai et analyserai en détail les résultats obtenus lors de la campagne d'étalonnage du Photomµetre PACS qui s'est achevée en Juin 2007. Enfin, je traduirai les mesures réalisées en laboratoire en terme de performances "observationnelles" du Photomµetre PACS.

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Teyssier, David. "Etalonnage de Herschel/HIFI : approche système et expérimentale d'un instrument scientifique spatial. Etude observationnelle de coeurs denses galactiques." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2002. http://tel.archives-ouvertes.fr/tel-00001957.

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L'étalonnage des instruments dédiés à l'observation de la Terre et du Cosmos est l'une des clefs d'un retour scientifique maximal de ces missions.
La première partie de cette thèse est consacrée à la préparation des outils et méthodes d'étalonnage du spectromètre submillimétrique HIFI embarqué à bord du satellite Herschel en 2007. Le premier aspect traite de l'étalonnage des données et de leur conversion en une échelle scientifique. Nous recensons dans un premier temps les besoins de l'étalonnage en vol et identifions les étalons primaires et secondaires. Nous établissons alors une liste de candidats potentiels, complétée par une campagne d'observations préparatoires au sol. Un schéma d'étalonnage interne fondé sur deux charges embarquées est étudié et nous présentons un premier bilan d'erreur. Nous montrons que cette approche n'est a priori pas adaptée aux conditions spatiales et donnons les premiers éléments d'une technique plus adéquate. Le second aspect s'intéresse à l'étalonnage de l'instrument proprement dit. Nous analysons les besoins de la campagne de mesures en laboratoire du premier prototype de HIFI, et proposons un système original afin d'étalonner divers paramètres au sol. Nous montrons également l'importance d'une modélisation instrumentale et présentons une description des systèmes d'ondes stationnaires susceptibles d'affecter les données de HIFI.
La seconde partie de cette thèse est dédiée à l'étude de coeurs denses galactiques détectés dans l'infrarouge moyen par le satellite ISO. Nous montrons que ces objets appartiennent à une population nouvelle de condensations massives (M > 1000 Masses solaires) et froides (8 < T < 25 K) associées à des nuages moléculaires géants. L'analyse indique des extinctions dans le visible supérieures à 50, et suggère que des phénomènes de collage sur les grain affectent la plupart des espèces moléculaires. Nous montrons que ces objets sont probablement fragementés, et qu'ils sont susceptibles, ou ont déjà initié la formation d'étoiles massives en leur sein.

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Sidhu, Jagjit Singh. "Probing Macroscopic Dark Matter Parameter Space." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1598956916361224.

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Zhu, Wei. "Microlens Mass Determinations from Space-based Parallax." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1498472350212665.

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Pope, Benjamin James Spinks. "Observing bright stars and their planets from the Earth and from space." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:d692bf96-ccf8-47bf-b246-1bbedcce60e5.

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The discovery and characterization of extrasolar planets is a leading frontier of science, which is limited by our ability to extract real astrophysical signals masked by systematic noise. In this Thesis I develop techniques for self-calibration in optical astronomy, in both imaging and photometry, applicable both to observations from the ground and for space telescopes, and apply these to searching for exoplanets. Kernel phase interferometry is a method for improving high angular resolution astronomical imaging by cancelling out the effects of the turbulent atmosphere. I derive a generalization, kernel amplitude, to correct also for the effects of scintillation, or twinkling. I go on to demonstrate kernel phase for the first time from the ground using the Palomar Hale 200-Inch Telescope, as a test case for the extreme adaptive optics instruments SPHERE and GPI. The Kepler satellite and its successor, the K2 mission, have been crucial to our understanding both of exoplanets, and via asteroseismology, of stellar physics. The success of K2 depends on correcting for its unstable pointing. Using semi-parametric Bayesian statistical models to overcome this issue, I report the discovery of 145 new transiting planet candidates in data from Campaigns 5 and 6 of the K2 mission. Furthermore, with two novel techniques, 'smear' and 'halo' photometry, which dramatically extend the dynamic range of Kepler and K2, I recover light curves of bright stars that were previously too saturated to study, and definitively detect variability in the seven naked-eye stars in the Pleiades cluster. These new data analysis approaches enable the K2 and TESS space missions to discover planets transiting the nearest and brightest stars, which will be ideal targets for the coming era of exoplanet characterization.

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Tanner, William Graydon. "Meteoroids and space debris hypervelocity impact penetrations : the role of hydrocodes." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319235.

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Trucks, Jesica Lynn. "A Variability Study of Y Dwarfs: A Spitzer Space Telescope Program." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1564689621551064.

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Yano, Hajime. "The physics and chemistry of hypervelocity impact signatures on spacecraft : meteoroids and space debris." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262370.

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Ekenbäck, Andreas. "Numerical modelling of ENAs from stellar wind interactions." Doctoral thesis, Institutet för rymdfysik (IRF), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1804.

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Energetic neutral atoms (ENAs) are produced whenever a stellar wind encounters a neutral atmosphere. If a stellar wind proton comes sufficiently close to a neutral a charge-exchange reaction may take place, transforming the proton into an ENA. Unaffected by magnetic and electric fields, ENAs provide an opportunity for global imaging of stellar wind interactions.

This thesis presents methods and results of numerical modelling of stellar wind interactions. In particular it treats in depth production of ENAs at comets, Mars and the extrasolar planet HD 209458b.

Sufficiently accurate numerical models of stellar wind interactions require extensive computations. Parallel computing has therefore been used throughout the work, both for fluid and particle simulations of space plasmas. This thesis describes the use of a general simulation tool, providing parallel computing for space plasma simulations.

The thesis presents estimations of the magnitude and morphology of the ENA production at comets and HD 209458b. It compares the results obtained with observations and analyzes them in the light of ENA production at similar objects. Also, simulated ENA images for Mars were produced and compared to observations.

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Brito, Miguel Centeno da Costa Ferreira. "Development of a miniature pulse tube cooler for space applications." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312193.

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Shrine, Nicholas Robert George. "Laboratory investigation of oblique hypervelocity impacts with relevance to in situ meteoroid and space debris detectors." Thesis, University of Kent, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301828.

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King, Barbara Amelia. "Space Art + Space Science a polymathic paradigm shift in the art/science dialogue." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/32739.

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Perhaps no other field of scientific endeavor has been more influenced by the arts than space exploration. The artistic visions of yesteryear are the technological realities of today. These realities in turn create new possibilities for artistic expression. However, Space Art and Space Science have shared a convoluted history. Their forerunner disciplines of the Humanities and Natural Sciences and their practitioners were entrenched as polar opposites for centuries. Recent research, however, has revealed the reverse; that the psychological profile and the creative processes of artists and scientists are actually similar, often to the point of the practitioners being polymathic. Moreover, it has been discovered that polymathic ability nurtures two qualities essential for the survival of both Space Art and Space Science: that of creativity and innovation. Current literature has taken note of the commonality of polymathic ability between the practitioners of the arts and sciences. Academic and industry think tanks have examined the virtues of artists as space researchers, and conversely, scientists developing an artistic approach as a design strategy. Thought leaders have expressed faith in trans-disciplinary collaboration as the way forward in the global affairs of space. Yet, therein lies the problem. These various studies individually lack a cohesive strategy to leverage their findings and transform the Art/Sci dialogue into a disruptive force that sustains a paradigm shift in the arts, space and society agendas going forward. The impetus for this dissertation is the unique opportunity to amalgamate those disparate studies by utilizing the momentum of New Space culture, and its focus on societal inclusion and environmental concerns to serve as anchors for space research and sustainability. Further, we argue that the next logical step is to inculcate a fundamental Art/Sci paradigm shift within the space community to exploit the unprecedented global drive towards space exploration and colonization, thereby solidifying the influence of the space art and space science agendas in the service of the global commons on Earth and in space.

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Tappe, Jack A. "Development of star tracker system for accurate estimation of spacecraft attitude." Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Dec/09Dec%5FTappe.pdf.

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Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, December 2009.
Thesis Advisor(s): Kim, Jae Jim ; Agrawal, Brij N. "December 2009." Description based on title screen as viewed on January 26, 2010. Author(s) subject terms: Star tracker, Planar triangles, Angle method, Spherical triangle, Quaternion estimator, Least-squares (QUEST), TRIAD Includes bibliographical references (p. 87-88). Also available in print.

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Baiocchi, Dave. "Design and control of lightweight, active space mirrors." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/290102.

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The success of the Hubble Space Telescope created a great interest in the next generation of space telescopes. To address this need, the University of Arizona (UA) has designed and built several lightweight prototype mirrors ranging in size from 0.5 m to 2 m in diameter. These mirrors consist of three key components: a thin, lightweight glass substrate holds the reflective surface; the surface accuracy is maintained by an array of position actuators; and the stiffness is maintained by a lightweight carbon-fiber/epoxy support structure. The UA mirrors are different from conventional mirrors in that they are actively-controlled: their figure may be changed after they leave the optics shop. This dissertation begins with an overview of the technical issues for placing large optics in space, and I also discuss the current state-of-the-art in active mirror design. Chapters 3 and 4 discuss ways to design mirrors such that the optical performance is maximized while the mass is minimized. Chapter 3 looks at the best way to distribute the mass between the reflective substrate and the actuators, and Chapter 4 looks at the optimum geometries for structured mirrors. The second half of this work looks at the practical aspects of controlling active mirrors. Chapter 5 discusses the University of Arizona's 2 m NMSD prototype mirror. Specifically, I review the system that I developed to measure and control the mirror. I also provide some details on using a least-squares solution to solve for the actuator commands. Chapter 6 discusses the UA ultralightweight 0.5 m prototype mirror. I describe the techniques that I developed for attaching loadspreaders to the reflective surface, the metrology system, and a software package used to remotely-control the mirror.

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Ridley, J. K. "Examination of the application of space-borne time-of-flight mass spectrometry to the analysis of cosmic dust particles." Thesis, University of Kent, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377578.

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Ballard, Sarah. "In Pursuit of New Worlds: Searches for and Studies of Transiting Exoplanets from Three Space-Based Observatories." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10229.

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This thesis presents studies of transiting exoplanets using observations gathered in large part from space, with the NASA EPOXI Mission, the Spitzer Space Telescope, and the Kepler Mission. The first part of this thesis describes searches for additional transiting planets in known exoplanet systems, using time series photometry gathered as part of the NASA EPOXI Mission. Using the EPOXI light curves spanning weeks for each star, we searched six exoplanetary systems for signatures of additional transiting planets. These six systems include five hosts to hot Jupiters: HAT-P-4, TrES-3, TrES-2, WASP-3, and HAT-P-7, and one host to a hot Neptune: GJ 436. We place upper limits on the presence of additional transiting planets in the super-Earth radius range for GJ 436 in Chapter 2, and in the Neptune-to-Saturn radius range for the other five systems in Chapter 4. Chapter 3 details a search for additional transits of a hypothesized planet smaller than the Earth, whose presence was suggested by the EPOXI observations of GJ 436. In that study, we demonstrate the sensitivity of Warm Spitzer observations to transits of a sub-Earth-sized planet. The fifth chapter details the characterization and validation of the Kepler-19 system, which hosts a transiting 2.2 \(R_{\bigoplus}\) planet, Kepler-19b. We demonstrate the planetary nature of the transit signal with an analysis that combines information from high-resolution spectroscopy, the shape of the transit light curve, adaptive optics imaging, and near-infrared transits of the planet. The sinusoidal variation in the transit times of Kepler-19b indicates the presence of an additional perturbing body, and comprises the first definitive detection of a planet using the transit timing variation method. While we cannot uniquely determine the mass and orbital period of Kepler-19c, we establish that its mass must be less than 6 times the mass of Jupiter. The sixth chapter presents evidence for the validation of a 2.0 \(R_{\bigoplus}\) planet residing in the habitable zone of a low-mass star, Kepler Object of Interest 1361.01. We discuss the theoretical composition of the planet, and address issues specific to habitability of planets orbiting M dwarfs.
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Pak, Anne On-Yi 1977. "Euclidean space codes as space-time block codes." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86722.

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Barry, Andrew Michael. "The science of science : programmes of British space research." Thesis, University of Sussex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333979.

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Watkinson, Emily Jane. "Space nuclear power systems : enabling innovative space science and exploration missions." Thesis, University of Leicester, 2017. http://hdl.handle.net/2381/40461.

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The European Space Agency’s (ESA’s) 241Am radioisotope power systems (RPSs) research and development programme is ongoing. The chemical form of the americium oxide ‘fuel’ has yet to be decided. The fuel powder will need to be sintered. The size and shape of the oxide powder particles are expected to influence sintering. The current chemical flow-sheet creates lath-shaped AmO2. Investigations with surrogates help to minimise the work with radioactive americium. This study has proposed that certain cubic Ce1-xNdxO2-(x/2) oxides (Ia-3 crystal structures with 0.5 < x < 0.7) could be potential surrogates for some cubic AmO2-(x/2) phases. A new wet-chemical-synthesis-based process for fabricating Ce1-xNdxO2-(x/2) with a targeted x-values has been demonstrated. It uses a continuous oxalate coprecipitation and calcination route. An x of 0.6 was nominally targeted. Powder X-ray diffraction (PXRD) and Raman spectroscopy confirmed its Ia-3 structure. An increase in precipitation temperature (25 °C to 60 °C) caused an increase in oxalate particle median size. Lath/plate-shaped particles were precipitated. Ce Nd oxide PXRD data was Rietveld refined to precisely determine its lattice parameter. The data will be essential for future sintering trials with the oxide where variations in its crystal structure during sintering will be investigated. Sintering investigations with micrometric CeO2 and Nd2O3 have been conducted to understand how AmO2 and Am2O3 may sinter. This is the first reported pure Nd2O3 spark plasma sintering (SPS) investigation. A comparative study on the SPS and the cold-press-and-sinter of CeO2 has been conducted. This is the first study to report sintering lath-shaped CeO2 particles. Differences in their sizes and specific surface areas affected powder cold-pressing and caused variations in cold-pressed-and-sintered CeO2 relative density and Vickers hardness. The targeted density range (85-90%) was met using both sintering techniques. The cold-press-and-sinter method created intact CeO2 discs with reproducible geometry and superior Vickers hardness to those made by SPS.

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McCalden, Alec John. "User interfaces in space science instrumentation." Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/14194/.

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This thesis examines user interaction with instrumentation in the specific context of space science. It gathers together existing practice in machine interfaces with a look at potential future usage and recommends a new approach to space science projects with the intention of maximising their science return. It first takes a historical perspective on user interfaces and ways of defining and measuring the science return of a space instrument. Choices of research methodology are considered. Implementation details such as the concepts of usability, mental models, affordance and presentation of information are described, and examples of existing interfaces in space science are given. A set of parameters for use in analysing and synthesizing a user interface is derived by using a set of case studies of diverse failures and from previous work. A general space science user analysis is made by looking at typical practice, and an interview plus persona technique is used to group users with interface designs. An examination is made of designs in the field of astronomical instrumentation interfaces, showing the evolution of current concepts and including ideas capable of sustaining progress in the future. The parameters developed earlier are then tested against several established interfaces in the space science context to give a degree of confidence in their use. The concept of a simulator that is used to guide the development of an instrument over the whole lifecycle is described, and the idea is proposed that better instrumentation would result from more efficient use of the resources available. The previous ideas in this thesis are then brought together to describe a proposed new approach to a typical development programme, with an emphasis on user interaction. The conclusion shows that there is significant room for improvement in the science return from space instrumentation by attention to the user interface.

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Godwin, Matthew Thomas. "The Skylark rocket, British space science and the European Space Research Organisation." Thesis, University of London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424926.

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Garrett, Susan R. "A mathematical model for the detection of deep space objects." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/90970.

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The problem of detecting deep space objects with certain probabilities was investigated. A mathematical model was then developed from given problem specifications that deals with the trade-off of various parameters involved in the detection problem. A software package that allows the user to input data interactively was written to implement the model. The completed program as well as an analysis of the tested results are included.
M.S.

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Bailer-Jones, Daniela M. "Scientific models : a cognitive approach with an application in astrophysics." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284998.

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Maharaj, Doraisamy Ashok. "Space for "development": US-Indian space relations 1955 -1976." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45973.

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Through four case studies of technological systems - optical tracking of satellites, sounding rockets, instructional television through a geosynchronous satellite, and a launch vehicle--I explore the origins and development of the Indian space program from 1955 through 1976, a period critical in shaping the program's identity and its relationship to the state. Institutionalized, and constructed in different geographic regions of India, these systems were embedded in the broader political, economic, and social life of the country and served as nodes around which existing and new scientific and technological communities were formed. These organic, highly networked communities in turn negotiated and developed a space program to meet the social and strategic demands of a new modernizing nation state. That modernizing program was, in turn, embedded in a broader set of scientific, technological and political relationships with industrialized countries, above all the United States. The United States' cooperation with India began with the establishment of tracking stations for plotting the orbits of artificial satellites. Cognizant of the contributions made by Indian scientists in the field of astronomy and meteorology, a scientific tradition that stretched back several decades, the officials and the scientific community at NASA, along with their Indian counterparts outlined a cooperative program that focused on the mutual exploration of the tropical space for scientific data. This initial collaboration gradually expanded and more advanced space application projects brought the two democratic countries, in spite of some misgivings, closer together in the common cause of using space sciences and technologies for developing India. In the process India and the United States ended up coproducing a space program that responded to the ambitions of the postcolonial scientific and political elite of India. The global Cold War and the ambiguities, desires and tensions of a postcolonial nation-state vying for leadership among the newly decolonized states in the Afro-Asian region are critical for understanding the origins and the trajectory of India's space program. Without this political context and the construction of a transnational web of relationships, it is highly unlikely that the Indian scientific and technological elite, along with their industrial and political partners, would have succeeded in putting India on the space map of the world.

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Bouland, Adam Michael. "The space around BQP." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113997.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 253-268).
This thesis explores the computational power of quantum devices from the perspective of computational complexity theory. Quantum computers hold the promise of solving many problems exponentially faster than classical computers. The computational power of universal quantum devices is captured by the complexity class BQP, which stands for "bounded-error quantum polynomial time." We hope that quantum devices will be capable of the full power of BQP in the long term. However, quantum computers are difficult to build, so the experimental devices of the near future may be incapable of universal quantum computation. As a result, a number of recent works have studied "weak" models of quantum computers which lie "below BQP." The first part of this thesis examines the space "below BQP" and describes a number of sub-universal models of quantum computation which can nevertheless perform sampling tasks which are difficult for classical computers. We show that prior models maintain hardness when their set of quantum operations is restricted, and describe two new models of "weak" quantum computation which also show advantage over classical devices. A major theme in this work is that almost any weak device can perform hard sampling tasks. We find that almost any model which is not universal, but not known to be efficiently classically simulable, admits a speedup over classical computing for sampling tasks under plausible assumptions. This work can be seen as progress towards classifying the power of all restricted quantum gate sets. On the other hand, quantum gravity theorists have considered modifying quantum mechanics to resolve the black hole information paradox. Inspired by these debates, the second part of this thesis explores the computational power of modified theories of quantum mechanics. We find that almost all modifications allow for drastically more power than BQP i.e. these modifications lie "above BQP" - and we find that these speedups may be related to superluminal signaling in these models. Surprisingly, we find one model which is only slightly more powerful than BQP. Inspired by this model, we study and resolve an open problem in classical complexity related to the power of statistical-zero knowledge proof systems.
by Adam Michael Bouland.
Ph. D.

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Gstalder, Steven Herbert. "Understanding Library Space Planning." Thesis, University of Pennsylvania, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10289537.

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The role of the academic library has shifted from developing book collections to serving the information and technology needs of students and faculty. The needs of library users change more quickly and unpredictably than the needs of books, and library directors have pushed beyond the traditional incremental approach to library development to respond to changing needs. As many universities struggle to balance budgets, library directors must demonstrate the value and demand for library spaces and services to justify investments in construction and renovation projects. This study investigates the reasons that the new library space projects were undertaken and the forces driving decisions about investments in the library facilities. The cases in this dissertation present studies of three private, non-profit liberal arts institutions in the Eastern United States that have recently invested in major renovation or construction projects for new library spaces. At each site, interviews and focus group sessions were conducted with librarians, students, faculty, and library administrators. Archival material was researched to supplement the data collected from the subjects of the interviews. A multi-lens framework of strategic change is used to examine the forces and factors that influenced the decisions to pursue new library spaces in each case study. The institutions in the study successfully developed new learning commons and library spaces through renovation or construction projects. Each of the libraries in the study faced similar factors leading to a new space, including overcrowding, interest from students in collaborative learning, increased demand for access to technology, and the decline in the use of the printed book. The strong leadership of the library director, with support from the institution’s president, contributed to the success of each project in the study. The importance of this study derives from its examination of the changing factors and forces that drive the uses of new library spaces, highlighting the need to build flexibility into new construction projects.

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Kumaran, Vikram. "Plan Recognition as Candidate Space Search." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-10312006-000347/.

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Effective human computer interaction is enhanced by a machine?s ability to make educated guesses about the intention of its user. In our research, we have developed a novel plan recognition algorithm ? based on plan space search planners ? to recognize plans given a limited set of observed actions. Our focus in this research is towards accurately picking possible plans and not towards disambiguation or building plan libraries and therefore we complement other advances in this field, namely probability based recognition and other plan library based recognition systems. Along with the ability to recognize overall goal of an agent our algorithm also allows us to make local predictions, a feature absent in most of the other system.

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Godwin, Matthew. "The Skylark rocket : British space science and the European space research organisation, 1957-1972 /." Paris : Beauchesne, 2007. http://catalogue.bnf.fr/ark:/12148/cb411905977.

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Dissertations / Theses on the topic 'Astrophysics and Space Science'

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