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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

A search for strong gravitational lenses in early-type galaxies using UKIDSS

Husnindriani, Prahesti January 2015 (has links)
This work is focused on a search for strong gravitational lenses in early-type galaxies (ETGs). The total number of samples is 4,706 galaxies encompassing a magnitude range 15.0 < i < 18.0 and colour 3.5 < (u-r) < 5.0. Two databases were employed as the source of K-band images (UKIDSS Large Area Survey) and g, r, i images (SDSS). All samples were fitted to a Sersic component and automatically processed using GALFIT (Peng et al. 2002; Peng et al. 2010) inside a Python script (Appendix A). The first classification generated 259 galaxies which are seen as single galaxies in their K-band images. These galaxies were then reclassified based on image contouring in g, r, i, and K filters and therefore resulted in three categories of samples: Sample A (99 galaxies), Sample B (96 galaxies), and Sample C (64 galaxies).
12

Web-enabled Spatial Decision Support System for Interdisciplinary Watershed Management

Regmi, Binaya 18 October 2002 (has links)
The development and use of web-enabled tools for watershed modeling and decision-making have gained popularity lately with the increase in internet speed and accessibility. Most of the web-enabled tools available today address the watershed problems related to a narrow discipline like hydrology, or ecology etc. This thesis presents the work done in the development of a web-enabled integrated system, named WebL2W, which can address watershed problems in a more holistic approach. WebL2W integrates models from hydrology, economics, and biology in a single shell. The integration is performed using GIS as a common platform for database and interface management. A user accesses the system over the web and chooses pre-selected land development patterns to create a 'what if' scenario. The hydrologic model simulates effects of the scenario on annual runoff volume, flood peaks of various return periods, and ground water recharge. The economics model evaluates the changes in land value, tax revenue, and government expenditures as a result of the new land development scenario. The biology model evaluates effects of new land uses to fish habitats in the watershed. The design of the system is based on current software engineering practices such as object oriented programming (OOP) and relational database management system (RDBMS). The implementation uses the Visual Basic programming environment and Active Server Pages. / Master of Science
13

Development of a Spatial Decision Support System for Emergency Medical Service Facility Siting

Muza, Matej 09 June 2011 (has links)
Improved strategic location of an Emergency Medical Service (EMS) facility can significantly increase EMS efficiency. Urban planners need to consider a location that satisfies multiple criteria in order to make an informed decision about a future EMS facility site. Apart from basic criteria such as parcel value and size, decision-makers need to consider area and population coverage from potential parcels. Geographic Information Systems (GIS) provide an adequate analysis environment for EMS facility siting as many considered criteria are of a spatial nature. However, urban planners making decisions about an EMS facility site often lack the necessary expertise to make full use of challenging GIS tools. In order to help urban planners in the analysis process, this research developed a Spatial Decision Support System (SDSS) for EMS facility siting. The system was developed in ESRI ArcGIS (9.3) using the Visual Basic for Applications (VBA) programming environment. The objective of the system was to integrate spatial data, analysis, and visualization in a single system to help users evaluate a facility siting problem. The system's performance was tested using data for the Town of Blacksburg, VA. In addition, the system was evaluated by local planners and GIS staff with experience in EMS facility siting. Planners agreed the system enables more comprehensive and straightforward use of GIS for EMS facility siting analysis than other available siting tools. Potential improvements include a simpler user interface, synthesis of geoprocessing techniques, reduction of analysis time through automation, and better decision-making by improved visualization of results. / Master of Science
14

Détermination de la masse des neutrinos cosmologiques avec les forêts Lyman-alpha / Determining the mass of cosmological neutrinos using Lyman-alpha forests

Baur, Julien 28 September 2017 (has links)
Les travaux présentés dans cette thèse contraignent la masse des neutrinos dans le contexte de 4 modèles de matière noire en utilisant le spectre de puissance du flux transmit dans les forêts Lyman-alpha des quasars distants. Les neutrinos laissent une emprunte sur les grandes structures dans l'Univers à travers l'échelle à laquelle ils diffusent, qui se manifeste comme un déficit de fluctuations de densité de matière sur des distances inversement proportionnelles à leur masse. De l'ordre de quelques Mpc, ces échelles peuvent être sondées par les forêts Ly-$alpha$ qui tracent la densité d'hydrogène neutre atomique suivant la ligne de visée du quasar en arrière-plan. J'utilise le spectre de puissance Ly-$alpha$ construit grâce à deux relevés de grandes structures:les $13,821$ spectres optiques de quasars basse-résolution de la 9ème publication des données du SDSS/BOSS à 12 redshifts de $langle z rangle = 2.2$ à $4.4$; ainsi que la centaine de spectres de quasar haute-résolution du relevé XQ-100 du VLT à $langle z rangle = 3.20, 3.56$ et $3.93$. Ces deux relevés nous permettent de sonder les échelles de $k geqslant 0.001~s/mathrm{km}$ à $k leqslant 0.02$ et $k leqslant 0.07~ s/mathrm{km}$ respectivement.Modéliser le spectre de puissance Ly-$alpha$ nécessite résoudre le régime non-linéaire de formation des structure et modéliser le gaz inter-galactique dans les simulations cosmologiques hydrodynamiques destinées à cet effet. Je contrôle pour plusieurs incertitudes systématiques liées à ces simulations. Dans un premier temps, je quantifie la variance d'échantillonnage à l'aide de simulations tournées avec différentes conditions initiales. Dans un second temps, je teste la validité d'une méthode permettant de construire le spectre de puissance à partir de simulations plus petites et moins résolues. Pour ce, j'ai tourné une simulation évoluant $2 times 2048^3$ particules de matière noire et de baryons dans un covolume de $(100~h^{-1}mathrm{Mpc})^3$. Ce travail a permit à notre groupe d'améliorer les contraintes sur la masse des neutrinos de $sum m_nu < 0.15~mathrm{eV}$ établie précédemment à $sum m_nu < 0.12~mathrm{eV}$ à $95%$ de vraisemblance. J'ai ensuite tourné mes efforts vers l'implémentation de neutrinos stériles en tant qu'un candidat matière noire non-froide dans les simulations. En particulier, j'ai produit les contraintes les plus fortes (au moment de la publication) sur la masse des neutrinos stériles en tant que matière noire tiède: $m_nu lesssim 25~mathrm{keV}$ à $95%$ de vraisemblance. J'ai étendu l'étude dans le contexte d'une matière noire mixte et contraint l'abondance relative de la composante tiède par rapport à la froide. Enfin, j'ai complété ce travail en permettant une résonance dans la production des neutrinos stériles, réduisant ainsi leur échelle caractéristique de diffusion et refroidissant la matière tiède qu'ils incorporent. A ce but, j'ai initié une collaboration avec une équipe de physiciens théoriques impliqués dans les recherches astrophysiques de ces neutrinos stériles dits produits par résonance dans des objets riches en matière noire. Notre jeune collaboration a établi les premières contraintes sur leur masse en utilisant le spectre de puissance Ly-$alpha$. / In the work presented in this thesis, I use the power spectrum of the transmitted flux in the Lyman-alpha (Ly-$alpha$) forest of distant quasars to constrain the mass of cosmological neutrinos in the context of four seperate projects. Neutrinos leave a signature imprint on large scale structures in the Universe through their free-streaming, which manifests as a deficit of matter density fluctuations on typical length scales that are inversely proportional to their rest mass. This typical free-streeming scale, of order a few Mpc, can be probed by Ly-$alpha$ forests which are imprints of the neutral atomic Hydrogen density along the background quasar's line-of-sight. I use the Ly-$alpha$ flux power spectrum from mainly two large scale structure surveys: the $13,821$ low-resolution quasar spectra from the ninth data release of SDSS (BOSS) in 12 redshift bins from $langle z rangle = 2.2$ to $4.4$; and the $100$ high-resolution quasar spectra from the XQ-100 survey (of the VLT's XShooter spectrograph) in 3 redshift bins, $langle z rangle = 3.20, 3.56$ and $3.93$. This enables us to probe scales from $k geqslant 0.001~s/mathrm{km}$ to $k leqslant 0.02$ and $k leqslant 0.07~ s/mathrm{km}$ respectively.Modeling the flux power spectrum requires solving the non-linear regime of structure formation and the intergalactic gas in the cosmological hydrodynamics simulations that are used to that effect. I controlled for several of many systematic uncertainties related to the simulations. First, I ran simulations with different initial conditions to quantify the sampling variance. I then tested the accuracy of a splicing technique that we use to construct the flux power spectrum from lower size and lower resolution simulations. This required producing a complete run of a $(100~h^{-1}mathrm{Mpc})^3$ comoving cube containing $2 times 2048^3$ dark matter particles and baryons. This enabled our working group to enhance the previously established constraints on the sum of neutrino masses from $sum m_nu < 0.15~mathrm{eV}$ to the most stringent constraint to date $sum m_nu < 0.12~mathrm{eV}$ with $95%$ confidence. I then worked on implementing right-handed neutrinos in non-cold dark matter cosmological frameworks. A substancial amount of work has gone into applying plausible initial conditions that would accurately model the free-streaming effect of these types of particles. I put the most stringest constraints (at the time of publication) on the mass of non-resonantly produced sterile neutrinos as pure warm dark matter candidates, $m_nu lesssim 25~mathrm{keV}$ at $95%$ confidence. I extended this investigation into a mixed warm plus cold dark matter cosmology. Finally, I implement right-handed neutrinos produced in presence of a lepton asymmetry which boosts their production and lowers their free-streaming scale. I started a collaboration with a team of theoretical physicists involved in searching for astrophysical evidence for the existance of such resonantly-produced right-handed neutrinos in dark matter rich systems. Our new-born collaboration has enabled the first ever constraints on their mass using the Ly-$alpha$ forest power spectrum.
15

Mesure de l'échelle des oscillations acoustiques de baryons dans la fonction de corrélation des forêts Lyman-α avec la distribution des quasars observés dans le relevé SDSS / Mesure of the scale of bayonic acoustic oscillations in the correlation function of Lyman-α forest with the quasar distribution observed in the SDSS survey

Du Mas des Bourboux, Hélion 08 September 2017 (has links)
La propagation des ondes acoustiques dans le plasma primordial a laissé son empreinte sous la forme d'un pic dans la fonction de corrélation à deux points de la densité de matière. Ce pic d'oscillations acoustiques de baryons (BAO) constitue une échelle standard permettant de déterminer certains paramètres des différents modèles cosmologiques.Dans ce manuscrit de thèse, nous présentons une mise à jour de la mesure de BAO à un redshift z=2.40, à l'aide de la fonction de corrélation croisée entre deux traceurs des fluctuations primordiales de densité de matière: les quasars de SDSS-III (BOSS) et leurs fluctuations d'absorption du flux des forêts Lyman-α. Ces fluctuations tracent la distribution d'hydrogène neutre dans le milieu intergalactique (IGM).Cette étude constitue le premier développement d'un ajustement entièrement physique de la fonction de corrélation croisée; il prend notamment en compte la physique des quasars et la présence d'éléments plus lourds que l'hydrogène dans l'IGM. Nous y présentons également les premières simulations de notre analyse. Celles-ci nous permettent de valider l'ensemble de la procédure de mesure de l'échelle BAO.Cette étude mesure la distance de Hubble et la distance de diamètre angulaire avec respectivement une précision de 2% et 3% (intervalle à 1 σ). Nous combinons nos résultats avec d'autres mesures de BAO à des redshifts plus faibles et trouvons la densité de matière noire et d'énergie noire dans le cadre de deux différents modèles cosmologiques: ΛCDM et oΛCDM. / The acoustic wave propagation in the primordial plasma left its imprint in the two-point correlation function of the matter density field. This baryonic acoustic oscillation (BAO) peak builds up a standard ladder allowing us to infer some parameters of the different cosmological models.In this thesis manuscript we present an update of the BAO measurement at a redshift z=2.40, from the cross-correlation function between two tracers of the primordial matter density fluctuations: quasars of SDSS-III (BOSS) and their Lyman-α-forest absorption fluctuations. These fluctuations trace the neutral hydrogen distribution in the intergalactic medium (IGM).This study gives the first developpment of the full physical fit of the cross-correlation. Among other effects, it takes into account quasar physics and the distribution of IGM elements heavier than hydrogen. We also present the first simulations of our analysis. They allow us to validate the overall data analysis leading to the BAO measurement.This study measures the Hubble distance and the angular diameter distance at the 2%$ and 3%$ precision level respectivelly (1 σ interval). We combine our results with other BAO measurements at lower redshifts and find the dark matter density and dark energy density in the framework of two different cosmological models: ΛCDM et oΛCDM.
16

PROBING THE INTERSTELLAR MEDIUM AND STAR FORMATION OF THE MOST LUMINOUS QUASAR AT z = 6.3

Wang, Ran, Wu, Xue-Bing, Neri, Roberto, Fan, Xiaohui, Walter, Fabian, Carilli, Chris L., Momjian, Emmanuel, Bertoldi, Frank, Strauss, Michael A., Li, Qiong, Wang, Feige, Riechers, Dominik A., Jiang, Linhua, Omont, Alain, Wagg, Jeff, Cox, Pierre 10 October 2016 (has links)
We report new IRAM/PdBI, JCMT/SCUBA-2, and VLA observations of the ultraluminous quasar SDSS J010013.02+280225.8 (hereafter, J0100+2802) at z =. 6.3, which hosts the most massive supermassive black hole (SMBH), 1.24 x 10(10) M circle dot, that is known at z > 6. We detect the [C II] 158 mu m fine structure line and molecular CO(6-5) line and continuum emission at 353, 260, and 3 GHz from this quasar. The CO(2-1) line and the underlying continuum at 32 GHz are also marginally detected. The [C II] and CO detections suggest active star formation and highly excited molecular gas in the quasar host galaxy. The redshift determined with the [C II] and CO lines shows a velocity offset of similar to 1000 km s(-1) from that measured with the quasar Mg II line. The CO (2-1) line luminosity provides a direct constraint on the molecular gas mass, which is about (1.0 +/- 0.3) x 10(10) M circle dot We estimate the FIR luminosity to be (3.5 +/- 0.7) x 10(12) L circle dot, and the UV-to-FIR spectral energy distribution of J0100 +2802 is consistent with the templates of the local optically luminous quasars. The derived [C II]-to-FIR luminosity ratio of J0100+2802 is 0.0010 +/- 0.0002, which is slightly higher than the values of the most FIR luminous quasars at z similar to 6. We investigate the constraint on the host galaxy dynamical mass of J0100 vertical bar 2802 based on the [C II] line spectrum. It is likely that this ultraluminous quasar lies above the local SMBH-galaxy mass relationship, unless we are viewing the system at a small inclination angle.
17

SDSS J163459.82+204936.0: A RINGED INFRARED-LUMINOUS QUASAR WITH OUTFLOWS IN BOTH ABSORPTION AND EMISSION LINES

Liu, Wen-Juan, Zhou, Hong-Yan, Jiang, Ning, Wu, Xufen, Lyu, Jianwei, Shi, Xiheng, Shu, Xinwen, Jiang, Peng, Ji, Tuo, Wang, Jian-Guo, Wang, Shu-Fen, Sun, Luming 05 May 2016 (has links)
SDSS J163459.82+204936.0 is a local (z = 0.1293) infrared-luminous quasar with L-IR = 10(11.91) L-circle dot. We present a detailed multiwavelength study of both the host galaxy and the nucleus. The host galaxy, appearing as an early-type galaxy in the optical images and spectra, demonstrates violent, obscured star formation activities with SFR approximate to 140 M-circle dot yr(-1), estimated from either the polycyclic aromatic hydrocarbon emission or IR luminosity. The optical to NIR spectra exhibit a blueshifted narrow cuspy component in H beta, He I lambda lambda 5876, 10830, and other emission lines consistently with an offset velocity of approximate to 900 km s(-1), as well as additional blueshifting phenomena in high-ionization lines (e.g., a blueshifted broad component of He I lambda 10830 and the bulk blueshifting of [O III].5007), while there exist blueshifted broad absorption lines (BALs) in Na I. D and He I lambda lambda 3889, 10830, indicative of the active galactic nucleus outflows producing BALs and emission lines. Constrained mutually by the several BALs in the photoionization simulations with Cloudy, the physical properties of the absorption line outflow are derived as follows: density 10(4) < n(H) less than or similar to 10(5) cm(-3), ionization parameter 10(-1.3) less than or similar to U 10(-0.7), and column density 10(22.5) less than or similar to N-H less than or similar to 10(22.9) cm(-2), which are similar to those derived for the emission line outflows. This similarity suggests a common origin. Taking advantages of both the absorption lines and outflowing emission lines, we find that the outflow gas is located at a distance of similar to 48-65 pc from the nucleus and that the kinetic luminosity of the outflow is 10(44)-10(46) erg s(-1). J1634+2049 has a off-centered galactic ring on the scale of similar to 30. kpc that is proved to be formed by a recent head-on collision by a nearby galaxy for which we spectroscopically measure the redshift. Thus, this quasar is a valuable object in the transitional phase emerging out of dust enshrouding as depicted by the coevolution scenario invoking galaxy merger (or violent interaction) and quasar feedback. Its proximity enables our further observational investigations in detail (or tests) of the co-evolution paradigm.
18

Milliarcsecond Imaging of the Radio Emission from the Quasar with the Most Massive Black Hole at Reionization

Wang, Ran, Momjian, Emmanuel, Carilli, Chris L., Wu, Xue-Bing, Fan, Xiaohui, Walter, Fabian, Strauss, Michael A., Wang, Feige, Jiang, Linhua 25 January 2017 (has links)
We report Very Long Baseline Array (VLBA) observations of the 1.5 GHz radio continuum emission of the z = 6.326 quasar SDSS J010013.02+ 280225.8 (hereafter J0100+ 2802). J0100+ 2802 is by far the most optically luminous and is a radio-quiet quasar with the most massive black hole known at z > 6. The VLBA observations have a synthesized beam size of 12.10 mas x5.36 mas (FWHM), and detected the radio continuum emission from this object with a peak surface brightness of 64.6 +/- 9.0 mu Jy beam(-1) and a total flux density of 88 +/- 19 mu Jy. The position of the radio peak is consistent with that from SDSS in the optical and Chandra in the X-ray. The radio source is marginally resolved by the VLBA observations. A 2D Gaussian fit to the image constrains the source size to (7.1 +/- 3.5) mas x (3.1 +/- 1.7) mas. This corresponds to a physical scale of (40 +/- 20) pc x (18 +/- 10) pc. We estimate the intrinsic brightness temperature of the VLBA source to be T-B = (1.6 +/- 1.2) x 10(7) K. This is significantly higher than the maximum value in normal star-forming galaxies, indicating an active galactic nucleus (AGN) origin for the radio continuum emission. However, it is also significantly lower than the brightness temperatures found in highest-redshift radio-loud quasars. J0100+ 2802 provides a unique example for studying the radio activity in optically luminous and radio-quiet AGNs in the early universe. Further observations at multiple radio frequencies will accurately measure the spectral index and address the dominant radiation mechanism of the radio emission.
19

Public Housing Tenant Relocation: Residential Mobility, Satisfaction, and the Development of a Tenant's Spatial Decision Support System.

Baker, Emma January 2002 (has links)
This study is an examination of residential mobility and its outcomes focussing on the forced relocation of public housing tenants from The Parks area of metropolitan Adelaide. In Euro-American countries, this type of residential mobility is increasingly used as a means of facilitating urban regeneration and countering the effects of the ongoing decrease in local public housing stock. The result is growing numbers of public tenants affected by relocation. The study agues that these public tenants have the right to a basic level of residential satisfaction, and in order for this satisfaction to be provided; the conditions and character of its formation must be understood. The thesis examines residential mobility and the formation of residential satisfaction to provide a basis for understanding the outcomes and effects of relocation, who is most affected, and how to target solutions to improve the relocation process. Despite the fact that households experience similar influences, and make their residential decisions in largely predictable ways, the formulation of residential satisfaction and the effects of relocation are highly individualised. Successful relocation is shown to be dependent on the inclusion of tenants' expert knowledge about their own residential satisfaction; this means that resident involvement in the process is crucial. This thesis investigates a means of combining these findings to improve the outcome of the relocation process for each individual tenant and their household. A prototype Spatial Decision Support System (SDSS) is constructed to allow relocating tenants to participate in their own relocation decision process. This SDSS allows local, spatially referenced information to be combined with each tenants own expert knowledge. This information is combined through a structured decision process, which is presented in a portable computer program with a simplified user interface. This SDSS is tested by relocating tenants and key stakeholders from The Parks to evaluate its usefulness in improving the relocation process. / Thesis (Ph.D.)--Geography and Environmental Studies, 2002.
20

Genetic Analysis of Bread Making Quality Stability in Wheat using a Halberd X Len Recombinant Inbred Line Population

Poudel, Ashima 2012 May 1900 (has links)
Wheat grain quality has a complex genetic architecture heavily influenced by the growing environment. Consistency in wheat quality not only affects the efficiency of milling and baking but also the quality of end-use products. The objectives of this study were to 1) analyze the different wheat quality parameters in Recombinant Inbred Lines (RILs) grown under different environments, and 2) to identify Quantitative Trait Loci (QTLs) associated with quality stability in RILs grown under different environments. A set of 180 RILs derived from two spring wheat lines 'Halberd' and 'Len' were grown at Uvalde and College Station TX, in the 2009/2010 growing season and at Chillicothe and College Station TX, in 2010/2011 growing seasons. The experiment was laid out in Randomized Complete Block Design (RCBD) with four replications within each location. Each line was tested for multiple quality traits that included grain hardness, protein content, dough mixing properties and bread baking quality using Single Kernel Characterization System (SKCS), Near-Infrared Reflectance Spectrometry (NIRS) analysis, mixograph and the Sodium Dodecyl Sulfate Sedimentation (SDSS) test. Genetic linkage map construction was carried out with 116 single nucleotide polymorphism (SNP) markers in the RILs. Then composite interval mapping was carried out to identify QTLs associated with quality traits. The SDSS column height was positively correlated across four environments. Similarly, it was found to have significant positive correlation with mixing tolerance and peak time within and also across locations. However, the SDSS was negatively correlated with the hardness index. The protein percent was not significant with any of the quality traits within and across environments. We were able to detect many QTLs for different quality traits but most of them were site specific. Only a few QTLs were consistent across environments. Most of the QTLs for quality traits i.e., SDSS, peak time, mixing tolerance and hardness index were identified on chromosome 1B. We were able to detect overlapped QTLs for SDSS column height and mixing tolerance on chromosome 1B. Furthermore, overlapping QTLs for mixing tolerance and peak time were detected on an unknown chromosome. We also detected overlapping QTLs for hardness index on chromosome 1B. We identified one stable QTL for SDSS column height on chromosome 4B. This QTL was detected based on the coefficient of variation (CV) for SDSS in four different environments.

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