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Tesis sobre el tema "Astrophysics Technique"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 31 de enero de 2023

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1

MacRae, John Hamish Kenneth. "The detection of very high energy cosmic gamma rays using the atmospheric Cerenkov technique." Thesis, Durham University, 1985. http://etheses.dur.ac.uk/7854/.

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This thesis is concerned with the detection of very high energy cosmic gamma rays using the atmospheric Cerenkov technique. A general introduction to gamma ray detection techniques is followed by a detailed discussion of the principles of the atmospheric Cerenkov technique and the history of its use prior to this work. The design and operation of the University of Durham facility in Dugway, Utah is described in depth. Monte Carlo computer simulations have been developed to assist in both the understanding of the equipment and the analysis of the results for the Durham facility. The variation o

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2

Tisserand, Patrick. "Recherches d'astres sombres massifs du halo galactique par la technique des microlentilles gravitationnelles avec les caméras d'EROS-2." Phd thesis, Université de Nice Sophia-Antipolis, 2004. http://tel.archives-ouvertes.fr/tel-00008267.

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Le problème de la masse manquante galactique prend sa source dans l'étude des courbes de rotation des galaxies spirales. Une des hypothèses privilégiées durant les vingt dernières années est la présence d'un halo entourant chaque galaxie composé d'objets compacts sombres (les machos) qui peuvent être détectés indirectement par le phénomène gravitationnel de microlentille. Le travail présenté dans cette thèse concerne l'analyse des courbes de lumière de plus de 55 millions d'étoiles des deux Nuages de Magellan, observées de juin 1996 à février 2003, avec les caméras de l'expérience EROS2. Deux

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3

Filip, Münz. "La simulation électronique de CELESTE : étude des biais et application à l'obsevation de la Nébuleuse de Crabe." Phd thesis, Université Paris-Diderot - Paris VII, 2003. http://tel.archives-ouvertes.fr/tel-00003334.

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Cette thèse présente le domaine de l'astronomie gamma et les principales sources de notre Galaxie (pulsars et SNRs) et celles situées à des distances cosmologiques (noyaux actifs de galaxie). La technique Cerenkov permet aux observatoires au sol de détecter des rayons gamma d'énergie du GeV absorbés dans l'atmosphère après avoir développé une cascade électromagnétique. Le projet CELESTE a atteint le but d'un seuil bas de 30 GeV, utilisant une grande surface de collection de l'ancienne centrale solaire de Thémis (Pyrénées Orientales). Une étude des principaux éléments du dispositif - un système

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4

Kreckelbergh, Stephane. "Contrôle longitudinal et caractérisation optique du détecteur Virgo." Phd thesis, Université Paris Sud - Paris XI, 2005. http://tel.archives-ouvertes.fr/tel-00012159.

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Le détecteur Virgo est constitué d'un interféromètre de Michelson avec des cavités Fabry-Perot de 3 km de long dans les bras et utilise la technique de recyclage de puissance. Il a pour but la détection directe des ondes gravitationnelles émises par des sources astrophysiques. <br />Pour atteindre sa sensibilité, Virgo doit être emmené à son point de fonctionnement par des asservissements tant longitudinaux qu'angulaires. Pour cela, nous avons mis en place un algorithme de contrôle longitudinal ("lock") qui partant d'un interféromètre libre l'emmène à son point de fonctionnement. Pour arriver

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5

Platts, Emma. "Computational analysis techniques using fast radio bursts to probe astrophysics." Doctoral thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33921.

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This thesis focuses on Fast Radio Bursts (FRBs) and presents computational techniques that can be used to understand these enigmatic events and the Universe around them. Chapter 1 provides a theoretical overview of FRBs; providing a foundation for the chapters that follow. Chapter 2 details current understandings by providing a review of FRB properties and progenitor theories. In Chapter 3, we implement non-parametric techniques to measure the elusive baryonic halo of the Milky Way. We show that even with a limited data set, FRBs and an appropriate set of statistical tools can provide reasonab

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6

Lindgren, Sara. "Metallicity determination of M dwarfs." Doctoral thesis, Uppsala universitet, Observationell astrofysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-332102.

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M dwarfs constitute around 70% of all stars in the local Galaxy. Their multitude together with their long main-sequence lifetimes make them important for studies of global properties of the Galaxy such as the initial mass function or the structure and kinematics of stellar populations. In addition, the exoplanet community is showing an increasing interest for those small, cold stars. However, very few M dwarfs are well characterized, and in the case of exoplanetary systems the stellar parameters have a direct influence on the derived planet properties. Stellar parameters of M dwarfs are diffic

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7

Sajjad, Saeeda. "Développement d'outils de simulation et de reconstruction de gerbes de particules pour l'astronomie gamma avec les futurs imageurs Tcherenkov." Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2007. http://tel.archives-ouvertes.fr/tel-00408835.

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Le futur de l'astronomie gamma au sol repose sur l'utilisation de grands réseaux d'imageurs Tcherenkov atmosphériques (IACT) avec des capacités améliorées : seuil en énergie plus bas, meilleure sensibilité, meilleurs résolution et pouvoir de rejet. Pour concevoir ces systèmes et optimiser leurs caractéristiques, il est nécessaire de comprendre les gerbes atmosphériques et de disposer d'outils de simulation adaptés permettant d'évaluer les performances des réseaux. La première partie de cette thèse traite des gerbes atmosphériques, des propriétés de la lumière Tcherenkov qu'elles émettent et de

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8

Popescu, Marcel. "Techniques d'observation spectroscopique d'astéroïdes." Phd thesis, Observatoire de Paris, 2012. http://tel.archives-ouvertes.fr/tel-00785991.

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L'objectif fondamental des sciences planétaires est la compréhension de la formation et de l'évolution du Système Solaire. Pour atteindre cet objectif les astéroïdes présentent un intérêt tout particulier pour la communauté scientifique. En effet, nous pouvons regarder la population astéroïdale comme une fenêtre vers le passée, par laquelle nous regardons les débuts de la formation du système planétaire. Ils sont les témoins des premiers moments de la formation des planètes gardant dans leur structure la complexité chimique de la nébuleuse primordiale. Pour cette raison, les études physiques e

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9

Adamakis, Sotiris. "Application of statistical analysis techniques to solar and stellar phenomena." Thesis, University of Central Lancashire, 2009. http://clok.uclan.ac.uk/20908/.

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Currently, solar observers are investigating spectroscopic images of the Sun's outermost atmosphere (the corona), which are challenging long-held views on the density and temperature structure of this environment. The corona is "filled" with magnetic strands but determining their precise nature is not straightforward. One way of revealing the nature of the coronal heating mechanism is by comparing simple theoretical one dimensional hydrostatic loop models with observations of the temperature and/or density structure along these features. The most wellknown method for dealing with comparisons l

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10

Hills, Graeme Lawrence. "The application of polarimetric techniques to gamma ray astronomy." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243187.

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11

Baker, Paul Thomas. "Distinguishing signal from noise| New techniques for gravitational wave data analysis." Thesis, Montana State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3596422.

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<p> The principal problem of gravitational wave detection is distinguishing true gravitational wave signals from non-Gaussian noise artifacts. We describe two methods to deal with the problem of non-Gaussian noise in the Laser Interferometer Gravitational Observatory (LIGO). </p><p> Perturbed black holes (BH) are known to vibrate at determinable quasi-normal mode frequencies. These vibrational modes are strongly excited during the inspiral and merger of binary BH systems. We will develop a template based search for gravitational waves from black hole ringdowns: the final stage of binary

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12

Collin, Gabriel L. W. H. "Neutrinos, neurons and neutron stars : applications of new statistical and analysis techniques to particle and astrophysics." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118817.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages [181]-205) and index.<br>The IceCube detector opens a new window into our universe; valuable for both astronomy and particle physics. This thesis spans a wide range of topics that are bound together by a common theme: the development and application of new statistical and computational methods for analysing data from particle and astrophysics experiments. Sterile neutrinos are a hypothetical fourth kind of neutrino, which are

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13

Hinz, Philip Mark. "Nulling interferometry for studying other planetary systems: Techniques and observations." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/280541.

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Nulling interferometry is an important technique in the quest for direct detection of extrasolar planets. It is central to NASA's plans for a Terrestrial Planet Finder (TPF) mission to detect and characterize Earth-like planets. This thesis presents the first experiments to demonstrate that the technique is a useful tool for ground-based observations as well. It demonstrates the ability of the technique to study faint, circumstellar environments otherwise not easily observed. In addition the observations and experiments allow more confident estimation of expected sensitivity to planetary syste

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14

Meli, Domenico Bertoloni. "The formation of Leibniz's techniques and ideas about planetary motion in the years 1688 to 1690." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293003.

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15

Evans, Thomas. "Characterising exoplanet atmospheres : Bayesian techniques for transit lightcurves." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:d5f10fa0-3ea1-45b4-bf97-3f43555de0ed.

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Precise measurements of transit lightcurves can be used to constrain the composition and structure of exoplanet atmospheres. Unfortunately, efforts to extract this information are usually hampered by the presence of correlated noise that is degenerate with the astrophysical signal of interest. A major theme of this thesis is the application of robust analysis methods to properly account for such degeneracies. In particular, I advocate the use of Bayesian inference for lightcurve fitting. For this study, the Bayesian framework is exploited by modelling lightcurves as Gaussian processes (GPs), w

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16

Kamil, Mohamed. "Spectroscopy of proton unbound states in 32Cl." University of the Western Cape, 2019. http://hdl.handle.net/11394/6615.

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>Magister Scientiae - MSc<br>This project aimed to investigate proton unbound states in 32Cl using the 32S(3He; t) charge-exchange reaction. This research is relevant both in the context of nuclear structure and astrophysics. Excited states in 32Cl up to Ex 6 MeV were produced using a 50 MeV 3He++ beam from the K200 separated sector cyclotron at iThemba LABS. The triton ejectiles were mass analysed and detected at the focal plane of the K600 magnetic spectrometer. An additional segmented silicon detector array called CAKE was used to detect the unbound protons from states in 32Cl in

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17

Fu, Nicole Christina. "Physical Properties of Massive, Star-Forming Galaxies When the Universe Was Only Two Billion Years Old." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19956.

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Due to the finite speed of light and a vast, expanding universe, telescopes are just now receiving the light emitted by galaxies as they were forming in the very early universe. The light from these galaxies has been redshifted (stretched to longer, redder wavelengths) as a result of its journey through expanding space. Using sophisticated techniques and exceptional multi-wavelength optical and infrared data, we isolate a population of 378 galaxies in the process of formation when the Universe was only two billion years old. By matching the distinctive properties of the light spectra of the

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18

Mehdi, Benna. "Génération et inversion de données de propagation d'ondes radio à travers un noyau comètaire (Experience CONSERT - Mission Spatiale ROSETTA)." Phd thesis, Université Paul Sabatier - Toulouse III, 2002. http://tel.archives-ouvertes.fr/tel-00007990.

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Ce memoire presente les modelisations directe et inverse entreprisent dans le cadre de la preparation de l'exploitation scientique de l'experience Consert de la mission spatiale Rosetta. Nous nous sommes interesses a la modelisation de la propagation d'ondes radio dans le cas simplifie d'un noyau cometaire a geometrie bidimentionnelle. A cette fin, une technique de trace de rayons (Ray Tracing Method, RTM) a ete developpee et validee par comparaison avec les resultats d'une methode spectrale (Pseudo Spectral Time Domain, PSTD). Cette technique a ete ensuite etendue au cas plus complexe d'une g

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19

Coates, Adam Ross. "Methods for ultra-broadband correlator development focusing on high-speed digital sampling techniques." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:8ace9e68-d8e7-4f1d-b6c9-13853eecbd47.

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In radio astronomy, a key limiting factor to observations made is the available bandwidth of the system. This thesis looks at two different approaches to building ultra-broadband correlators for use in radio astronomy. The first was a 2-20GHz double-sideband complex analogue correlator that was constructed before the work of this thesis. Characterisation tests are performed and a basic calibration is attempted. Both these sets of experiments show good results, with the basic calibration successfully being able to compensate for gain difference between the lags over a reduced bandwidth range us

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20

Long, Zachary. "Investigating the Physical Properties of Circumstellar Disks Using High Angular Resolution Observational Techniques." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535705067531455.

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21

Robustini, Carolina. "Study of peacock jets observed above a sunspot light-bridge : results and techniques." Licentiate thesis, Stockholms universitet, Institutionen för astronomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-137687.

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22

Robustini, Carolina. "Study of peacock jets observed above a sunspot light-bridge : results and techniques." Licentiate thesis, Stockholms universitet, Institutionen för astronomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-136516.

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23

Grier, Jennifer Ann. "Determining the ages of impact events: Multidisciplinary studies using remote sensing and sample analysis techniques." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284058.

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The determination of the timing of impact events and the ages of cratered planetary surfaces is a complex and challenging undertaking. A powerful approach to this endeavor is a multidisciplinary study; understanding and using data from both rock samples and remote sensing. Shocked material (especially melt material) found in meteorites like Orvinio provides critical material dating impact craters. Orvinio, in spite of a complex degassing history shows evidence for multiple impacts at 4.2 Ga, 7.5 Ma, and possibly 330 Ma. Correlating impact histories for inner solar system bodies and the asteroi

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24

Testov, Dmitry. "Effect of shell closure N = 50 and N = 82 on the structure of very neutron-rich nuclei produced at ALTO : measurements of neutron emission probabilities and half lives of nuclei at astrophysical r-processes path." Phd thesis, Université Paris Sud - Paris XI, 2014. http://tel.archives-ouvertes.fr/tel-01059803.

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Nowadays we are all witnesses of a competition of facilities at different countries to study unknown regions of neutron rich nuclei. Much efforts are devoted to understand the role of neutron excess and its influence on nuclei in vicinity of closed neutron shells. One of the means to investigate nuclear structure is in beta-decay. Once a nucleus is proven to exist, its beta-decay properties, such as T1/2 and Pn (probability of beta-delayed neutron emission), which are relatively easy to measure, can provide the first hints on the nuclear structure. On the r-process site, "waiting points"(nucle

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25

Morris, Chad Michael. "Detection Techniques of Radio Emission from Ultra High Energy Cosmic Rays." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1254506832.

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26

Corn, Philip B. "Measurement of the ⁸Li(d,n)⁹Be and ⁸Li(a,n)¹¹B reaction cross sections at astrophysical energies by radioactive beam techniques /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487671108308862.

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27

Ramiaramanantsoa, Tahina, Anthony F. J. Moffat, Robert Harmon та Richard Ignace. "BRITE-Constellation High-Precision Time-Dependent Photometry of the Early O-Type Supergiant ζ Puppis Unveils the Photospheric Drivers of Its Small- and Large-Scale Wind Structures". Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/2724.

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From 5.5 months of dual-band optical photometric monitoring at the 1 mmag level, BRITE-Constellation has revealed two simultaneous types of variability in the O4I(n)fp star ζ Puppis: one single periodic non-sinusoidal component superimposed on a stochastic component. The monoperiodic component is the 1.78-d signal previously detected by Coriolis/Solar Mass Ejection Imager, but this time along with a prominent first harmonic. The shape of this signal changes over time, a behaviour that is incompatible with stellar oscillations but consistent with rotational modulation arising from evolving brig

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28

Safsten, Emily Diane. "Using Advanced PSF Subtraction Techniques on Archival Data of Herbig Ae/Be Stars to Search for New Candidate Companions." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6967.

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Herbig Ae/Be (HAeBe) stars are intermediate mass (2-10 solar mass) pre-main sequence stars with circumstellar disks. Observing planets within these young disks would greatly aid in understanding planet formation processes and timescales particularly around massive stars. So far, only one planet, HD 100546 b, has been confirmed to orbit a HAeBe star. With over 250 HAeBe stars known, and several observed to have disks with structures thought to be related to planet formation, it seems likely that there are as yet undiscovered planetary companions within the circumstellar disks of some of thes

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29

Young, Joshua Michael. "Synthesis, Modification, and Analysis of Silicate Cosmic Dust Analogues Using Ion-Beam Techniques." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1707354/.

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Silicates analogous to cosmic dust were synthesized, modified, and analyzed utilizing ion-beam techniques with Rutherford backscattering spectrometry (RBS) and x-ray diffraction (XRD). Silicate dust is a common constituent in interstellar space, with an estimated 50% of dust produced in the stellar winds of M class Asymptotic Giant Branch (AGB) stars. Silicate dust acts as a surface upon which other chemicals may form (water ice for example), increasing significance in the cosmochemistry field, as well as laboratory astrophysics. Silicate formation in the stellar winds of AGB stars was simulat

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30

Anderson, Brian Eric. "Derivation of Moving-Coil Loudspeaker Parameters Using Plane Wave Tube Techniques." BYU ScholarsArchive, 2004. https://scholarsarchive.byu.edu/etd/17.

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Small-signal moving-coil loudspeaker driver parameters are traditionally derived through electrical impedance measurement techniques. These parameters are commonly called Thiele/Small parameters, after Neville Thiele and Richard Small who are credited with developing industry-standard loudspeaker modeling techniques. However, because loudspeaker drivers are electro-mechano-acoustical transducers, it should be possible to measure their parameters in physical domains other than the electrical domain. A method of measuring loudspeaker parameters from the acoustical domain will be developed. The t

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31

Fraser, Eric M. "Deep-UV Light Emitting Diodes: An Experimental Investigation of Characterization and Optimization Techniques." Scholarship @ Claremont, 2005. http://scholarship.claremont.edu/pomona_theses/11.

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Light emitting diodes (LEDs) and laser diodes (LDs) have many advantages over conventional light sources. Current commercial LEDs span the spectrum from IR to near- UV. There are a variety of applications for devices that extend into the deep-UV, including biological agent detection and optical storage. The nitride material system is a set of semiconducting compounds that have wavelengths that span a broad range, from yellow to deep-UV. AlGaN has a direct bandgap that extends into the deep-UV range; we will try to grow device-quality material, deposited epitaxially using metalorganic ch

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32

Hicks, Stacy Jo. "Characterization of Eight Potentially Hazardous Near Earth Asteroids: Rotation Period Analysis and Structure Modeling Via Light Curve Inversion Techniques." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/3060.

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The term “homeland security”, seems to have become synonymous with terrorism in the minds of the general public. However, there are other threats to the security of the United States homeland that can be just as, if not more, devastating than terrorism. Included among these other threats is the potential of an asteroid collision with Earth. Historically, asteroid impact events have been responsible for the devastation of our planet and many of the mass extinction events encountered throughout the geologic record. Knowledge of physical parameters such as structure and rotational dynamics of the

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33

Galliano, Frédéric. "Étude Multi-Longueurs d'Onde de Galaxies Naines Proches: Propriétés des Milieux Interstellaires de Faible Métallicité." Phd thesis, Université Paris Sud - Paris XI, 2004. http://tel.archives-ouvertes.fr/tel-00122609.

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Cette thèse est consacrée à l'observation multi-longueurs d'onde et à la modélisation des poussières, dans les galaxies naines locales de faible métallicité. Les principales motivations d'un tel projet sont : (i) l'étude des propriétés des poussières - composition, distribution de taille, etc. - dans des milieux interstellaires de métallicité non solaire ; (ii) l'étude de distributions spectrales d'énergie globales de galaxies naines qui, de par leur précocité chimique, présentent des analogies avec les galaxies primordiales que l'on ne peut pas observer ; et (iii) l'obtention d'informations s

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34

Byrum, Laura E. "Analysis of GaN/AlxGa1−xN Heterojunction Dual-Band Photodetectors Using Capacitance Profiling Techniques." Digital Archive @ GSU, 2009. http://digitalarchive.gsu.edu/phy_astr_theses/6.

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Capacitance-voltage-frequency measurements on n+-GaN/AlxGa1−xN UV/IR dual-band detectors are reported. The presence of shallow Si-donor, deep Si-donor, and C-donor/N-vacancy defect states were found to significantly alter the electrical characteristics of the detectors. The barrier Al fraction was found to change the position of the interface defect states relative to the Fermi level. The sample with Al fraction of 0.1 shows a distinct capacitance-step and hysteresis, which is attributed to C-donor/N-vacancy electron trap states located above the Fermi level (200 meV) at the heterointerface; w

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35

Flitti, Farid. "Techniques de réduction de données et analyse d'images multispectrales astronomiques par arbres de Markov." Phd thesis, Université Louis Pasteur - Strasbourg I, 2005. http://tel.archives-ouvertes.fr/tel-00156963.

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Le développement de nouveaux capteurs multispectraux en imagerie astronomique permet l'acquisition de données d'une grande richesse. Néanmoins, la classification d'images multidimensionnelles se heurte souvent au phénomène de Hughes : l'augmentation de la dimensionnalité s'accompagne d'un accroissement du nombre de paramètres du modèle et donc inévitablement une baisse de précision de leur estimation entrainant une dégradation de la qualité de la segmentation. Il est donc impératif d'écarter l'information redondante afin de réaliser des opérations de segmentation ou de classification robustes.

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36

Soriano, Melanie. "Astérosismologie d'étoiles de séquence principale ou évoluées, en relation avec l'expérience spatiale CoRoT, et les instruments au sol HARPS et SOPHIE." Phd thesis, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00438082.

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Le travail présenté dans cette thèse porte sur l'astérosismologie des étoiles de type solaire, et plus particulièrement des étoiles centrales de systèmes planétaires. L'analyse des ondes se propageant dans ces étoiles permet de mieux contraindre leur structure interne. Les deux premiers chapitres décrivent la théorie des oscillations stellaires et les outils numériques utilisés. La troisième partie traite de HD 52265, étoile cible de la mission CoRoT possédant une planète. Nous avons calculé des modèles préliminaires de cette étoile, en tenant compte des contraintes spectroscopiques, et nous a

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37

Chaty, Sylvain. "Étude multi-longueur d'onde du microquasar GRS 1915+105 et de sources binaires de haute énergie de la Galaxie." Phd thesis, Université Paris Sud - Paris XI, 1998. http://tel.archives-ouvertes.fr/tel-00003559.

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Cette thèse est consacrée à l'étude des microquasars, des sources binaires de haute énergie appartenant à notre Galaxie, analogues morphologiquement aux quasars, mais sur des échelles de longueur et de masse considérablement inférieures. La première partie concerne l'un des meilleurs représentants des microquasars: GRS 1915+105, découvert par le télescope WATCH/GRANAT, et qui présente des mouvements en apparence superluminiques. Nous avons établi la nature galactique de cette source, située à une distance de 12.5 +/- 1.5 kpc, ainsi que son environnement, à partir des observations millimétrique

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38

Escobar, María Eliana. "Astérosismologie des étoiles de type solaire, avec ou sans planètes, abondance des éléments et phénomènes de transport." Phd thesis, Université Paul Sabatier - Toulouse III, 2013. http://tel.archives-ouvertes.fr/tel-00909055.

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Depuis plusieurs décennies, les observations des oscillations stellaires et la recherche d'exoplanètes se sont développées en parallèle, en utilisant les mêmes méthodes et les mêmes instruments : la méthode de vitesse radiale, à partir d'instruments au sol comme SOPHIE à l'OHP ou HARPS au Chili, et la méthode photométrique, à partir d'instruments spatiaux, comme CoRoT et Kepler. L'intérêt d'étudier les oscillations des étoiles centrales de systèmes planétaires est apparu dès le début de ces observations. La caractérisation des planètes nécessite une très bonne connaissance de l'étoile centrale

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39

Nguyen, Catherine. "Development of squeezing techniques for quantum noise reduction in gravitational-wave detectors." Thesis, Université Paris Cité, 2021. http://www.theses.fr/2021UNIP7129.

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Le bruit quantique est une des limitations principales des détecteurs interférométriques d'ondes gravitationnelles, comme Virgo et LIGO. Réduire le bruit quantique a un impact direct sur la portée scientifique des futurs détecteurs d'ondes gravitationnelles (Advanced Virgo +, Advanced LIGO+, Einstein Telescope, Cosmic Explorer). L'origine du bruit quantique réside dans la nature quantique de la lumière, et en particulier dans les fluctuations du vide qui entrent par la sortie de l'interféromètre. Actuellement, l'injection d'états de vide comprimé (squeezing indépendant de la fréquence) dans Vi

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40

Galicher, Raphaël. "Étude de techniques d'imagerie à haut contraste basées sur la cohérence." Phd thesis, Université Paris-Diderot - Paris VII, 2009. http://tel.archives-ouvertes.fr/tel-00436293.

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Depuis 1995, environ 350 exoplanètes ont été détectées mais seule une dizaine l'a été directement pour plusieurs raisons. D'abord, les projections de l'étoile hôte et de sa planète sur la sphère céleste sont très proches -- quelques fractions de secondes d'arc. Ceci impose un diamètre minimum pour le télescope et un système compensant les perturbations atmosphériques. Ensuite, le flux lumineux de l'étoile hôte est entre un million et dix milliards de fois plus fort que celui de la planète. Pour réduire ce flux stellaire sans affecter le flux planétaire, nous utilisons un coronographe dont les

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41

Burke, Christopher J. "Survey for transiting extrasolar planets in stellar systems stellar and planetary content of the Open Cluster NGC 1245 /." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1132168623.

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42

Joner, Michael Deloss. "High-Quality Broadband BVRI Photometry of Benchmark Open Clusters." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2495.

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Photometric techniques are often used to observe stars and it can be demonstrated that fundamental stellar properties can be observationally determined using calibrated sets of photometric data. Many of the most powerful techniques utilized to calibrate stellar photometry employ the use of stars in clusters since the individual stars are believed to have many common properties such as age, composition, and approximate distance. Broadband photometric Johnson/Cousins BVRI observations are presented for several nearby open clusters. The new photometry has been tested for consistency relative to a

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43

St-Louis, Nicole, Patrick Tremblay, and Richard Ignace. "Polarization Light Curve Modeling of Corotating Interaction Regions in the Wind of the Wolf-Rayet Star Wr 6." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/2690.

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The intriguing WN4b star WR 6 has been known to display epoch-dependent spectroscopic, photometric and polarimetric variability for several decades. In this paper, we set out to verify if a simplified analytical model in which corotating interaction regions (CIRs) threading an otherwise spherical wind is able to reproduce the many broad-band continuum light curves from the literature with a reasonable set of parameters. We modified the optically thin model developed by Ignace, St-Louis & Proulx-Giraldeau to approximately account for multiple scattering and used it to fit 13 separate data sets

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Stevance, H. F., Richard Igance, P. A. Crowther, J. R. Maund, B. Davies, and G. Rate. "Probing the Rotational Velocity of Galactic WO Stars with Spectropolarimetry." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/5506.

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Oxygen sequence Wolf-Rayet stars (WO) are thought to be the final evolution phase of some high-mass stars, as such they may be the progenitors of Type Ic SNe as well as potential progenitors of broad-lined Ic and long gamma-ray bursts. We present the first spectropolarimetric observations of the Galactic WO stars WR93b and WR102 obtained with FORS1 on the Very Large Telescope. We find no sign of a line effect, which could be expected if these stars were rapid rotators. We also place constraints on the amplitude of a potentially undetected line effect. This allows us to derive upper limits on t

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45

Mate, Sujay. "Développement d'un simulateur du ciel pour les instruments à grand champ de vue X-gamma en orbite terrestre basse : application à l'évaluation des performances du spectro-imageur SVOM-ECLAIRs." Thesis, Toulouse 3, 2021. http://www.theses.fr/2021TOU30031.

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Les sursauts gamma (Gamma-Ray Bursts ou GRBs) sont les explosions les plus lumineuses de l'univers. On les observe sous la forme de bouffées de rayons X/ƴ (d'une durée de quelques millisecondes à quelques dizaines de secondes) suivies d'une émission rémanente (généralement à de plus grandes longueurs d'onde). Ils résultent soit de la fusion de deux objets compacts (une paire d'étoiles à neutrons ou une étoile à neutrons et un trou noir), soit de l'effondrement du noyau d'une étoile massive (>15 masse solaire). Les GRBs sont d'excellents candidats pour étudier la physique aux énergies et den

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Shrestha, Manisha, Hilding R. Neilson, Jennifer L. Hoffman, and Richard Ignace. "Polarization Simulations of Stellar Wind Bow Shocks. I. The Case of Electron Scattering." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/2691.

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Bow shocks and related density enhancements produced by the winds of massive stars moving through the interstellar medium provide important information regarding the motions of the stars, the properties of their stellar winds, and the characteristics of the local medium. Since bow-shock nebulae are aspherical structures, light scattering within them produces a net polarization signal even if the region is spatially unresolved. Scattering opacity arising from free electrons and dust leads to a distribution of polarized intensity across the bow-shock structure. That polarization encodes informat

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47

Papakonstantinou, Nikolaos. "Investigation of variable Ap Stars in TESS continuous viewing zone." Thesis, Uppsala universitet, Observationell astrofysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-441349.

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Hubrig, S., K. Scholz, Wolf-Rainer Hamann, M. Schöller, Richard Ignace, I. Ilyin, K. G. Gayley, and Lidia M. Oskinova. "Searching for a Magnetic Field in Wolf-Rayet Stars Using FORS 2 Spectropolarimetry." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etsu-works/2694.

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To investigate if magnetic fields are present in Wolf–Rayet stars, we selected a few stars in the Galaxy and one in the Large Magellanic Cloud (LMC). We acquired low-resolution spectropolarimetric observations with the European Southern Observatory FORS 2 (FOcal Reducer low dispersion Spectrograph) instrument during two different observing runs. During the first run in visitor mode, we observed the LMC Wolf–Rayet star BAT99 7 and the stars WR 6, WR 7, WR 18, and WR 23 in our Galaxy. The second run in service mode was focused on monitoring the star WR 6. Linear polarization was recorded immedia

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Neilson, Hilding, Richard Ignace, Beverly Smith, Gary Henson, and Alyssa Adams. "Evidence of a Mira-like tail and bow shock about the semi-regular variable V CVn from four decades of polarization measurements." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/6233.

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Polarization is a powerful tool for understanding stellar atmospheres and circumstellar environments. Mira and semi-regular variable stars have been observed for decades and some are known to be polarimetrically variable, however, the semi-regular variable V Canes Venatici displays an unusually large, unexplained amount of polarization. We present ten years of optical polarization observations obtained with the HPOL instrument, supplemented by published observations spanning a total interval of about forty years for V CVn. We find that V CVn shows large polarization variations ranging from 1 -

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Lai, Olivier. "L'optique adaptative du Telescope Canada France Hawaii et son utilisation pour l'etude des coeurs de galaxies a flambee d'etoiles." Phd thesis, Université Paris-Diderot - Paris VII, 1996. http://tel.archives-ouvertes.fr/tel-00003538.

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L'optique adaptative est une technique qui permet de corriger en temps reel des defauts introduits par la turbulence atmospherique sur les images produites par un telescope. Les instruments ont maintenant atteint une maturite suffisante pour que des systemes de seconde generation apparaissent. Le Telescope Canada France Hawaii s'est equipe d'une optique adaptative a mesure et controle de courbure. Son integration et csa caracterisation en laboratoire et sur le ciel constituent la permiere partie de cette these. La philosophie et la methodologie d'integration sont exposes, ainsi que les resulta

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