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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.
581

Effective School Characteristics And Student Achievement Correlates As

Doran, James 01 January 2004 (has links)
The purpose of this study is to investigate the relationships between effective school characteristics and norm referenced standardized test scores in American-style international schools. In contrast to schools in traditional effective schools research, international schools typically have middle to high SES families, and display average to above average achievement. Eleven effective school characteristics were identified and correlated with standardized test scores for grades 4, 6, and 8 and high school SAT scores. Data was gathered from an online teacher questionnaire designed for this study. All eleven characteristics were present in high performing international schools while frequent analysis of student progress, high academic expectations and positive school environment were more prominent. Positive school environment, high academic expectations, strong instructional leadership and cultural diversity were chosen as important characteristics of an effective international school. Learning time is maximized was the only characteristic that was significantly correlated with achievement and only in grades 4, 6 and 8. There was no statistically significant relationship found between norm referenced test scores and the aggregate effective school characteristics score.
582

Evaluating the Leachability of Elements from Residuals Generated by Hydraulic Fracturing in Marcellus Shale

Swann, Christina Talbot 25 June 2015 (has links)
The purpose of this research was to characterize the residual solids produced from hydraulic fracturing operations in the Marcellus Shale region. Four field samples were evaluated: drilling mud, treated sludge from the chemical treatment of process water, solids from the gravity settling of produced water, and sludge solidified prior to disposal in a municipal landfill. Cement kiln dust (CKD), used for solidification, was also considered in this study. All samples were subjected to a variety of laboratory techniques to determine their elemental composition and the potential for the elements to leach from the landfill. Strong acid digestion using a 3:1 combination of nitric acid to hydrochloric acid in a microwave with closed vessels was used to determine overall elemental composition. Leaching experiments were performed with de-ionized water and acetic acid (0.57%, pH 2.88) in an attempt to respectively evaluate the effects of weak and strong fluids that might be encountered by the residuals in landfill environments. Elements were analyzed by means of ICP-MS revealing the increased tendency for alkali metals, alkaline earth metals and halogens to leach. Leachablility was further increased for metals when exposed to acidic conditions. / Master of Science
583

An Analysis of the Effect of Early Season Winning Percentage on Final Regular Season Winning Percentage

Emily, Martin M. January 2019 (has links)
No description available.
584

Development of an Advanced Two-Dimensional Microdosimetric Detector based on THick Gas Electron Multipliers / Development of an Advanced 2D THGEM Microdosimetric Detector

Darvish-Molla, Sahar January 2016 (has links)
The THick Gas Electron Multiplier (THGEM) based tissue-equivalent proportional counter (TEPC) has been proven to be useful for microdosimetry due to its flexibility in varying the gaseous sensitive volume and achieving high multiplication gain. Aiming at measuring the spatial distribution of radiation dose for mixed neutron-gamma fields, an advanced two-dimensional (2D) THGEM TEPC was designed and constructed at McMaster University which will enable us to overcome the operational limitation of the classical TEPCs, particularly for high dose rate fields. Compared to the traditional TEPCs, anode wire electrodes were replaced by THGEM layer, which not only enhances the gas multiplication gain but also offers a flexible and convenient fabrication or building 2D detectors. The 2D THGEM TEPC consists of an array of 3×3 sensitive volumes, equivalent to 9 individual TEPCs, each of which has a dimension of 5 mm diameter and length. Taking the overall cost, size and flexibility into account, to process 9 detectors signals simultaneously, a multi-input digital pulse processing system was developed by using modern microcontrollers, each of which is coupled to a 12-bit sampling ADC with a sampling rate of 42 Msps. The signal processing system was tested using a NaI(Tl) detector, which has proven that is it faster than a traditional analogue system and a commercial digital system. Using the McMaster Tandetron 7Li(p,n) accelerator neutron source, both fundamental detector performance, as well as neutron dosimetric response of the 2D THGEM TEPC, has been extensively investigated and compared to the data acquired by a spherical TEPC. It was shown that the microdosimetric response and the measured absorbed dose rate of the 2D THGEM detector developed in this study are comparable to the standard 1/2" TEPC which is commercially available. / Thesis / Doctor of Philosophy (PhD)
585

Исследование личностных особенностей спортсменов-лыжников : магистерская диссертация / Research of personal features of sportsmen-skiers

Кабаева, М. А., Kabaeva, M. A. January 2019 (has links)
The object of the study was athletes involved in cross-country skiing. The subject of the study was personal features that affect the success of athletes-skiers. The master's thesis consists of an introduction, two chapters, conclusion, a list of literature (67 sources) and applications, including forms of applied techniques, the classifier of associative connections, and the scheme of volitional action. The volume of the master's thesis is 78 pages, on which are placed 19 tables. The introduction reveals the relevance of the research problem, the development of the problem, the purpose and objectives of the research, the object and subject of the research, the main hypothesis are formulated, the methods and the empirical base are specified. The first and second chapters include a review of foreign and domestic literature on the topic of the study. The first chapter include a review of foreign and domestic literature on the topic of the study. It describes the specifics of sports activities, professional and important qualities of athletes to the study of personal characteristics of athletes. Conclusions on the first chapter is the results of the study of theoretical material. The second chapter is devoted to the empirical part of the study. It describes the organization and methods studies and the results obtained for all methodologies used: -methods of diagnostics of personality on motivation to success by T. Ehlers; - the scale of personal and situational anxiety C. D. Spielberg - Hanin Y. L.; - questionnaire level of subjective control (UIC) John. Rotter; - questionnaire "Evaluation of level of aspiration" V. K. Gerbachevsky; - test questionnaire of A. V. Zverkov and E. V. Eidman "Study of volitional self-regulation". The conclusions of Chapter 2 include the main results of the empirical study. In conclusion, the results of the theoretical and empirical parts of the work, as well as conclusions on the hypotheses put forward, the practical significance of the study. / Объектом исследования являются спортсмены, занимающиеся лыжными гонками. Предметом исследования стали личностные особенности, влияющие на успешность спортсменов-лыжников. Магистерская диссертация состоит из введения, двух глав, заключения, списка литературы (67 источников) и приложений, включающих в себя бланки применявшихся методик и результаты проведенного исследования. Объем магистерской диссертации 78 страниц, на которых размещены 19 таблиц. Во введении раскрывается актуальность проблемы исследования, разработанность проблематики, ставятся цель и задачи исследования, определяются объект и предмет исследования, формулируется основная гипотеза, указываются методы и эмпирическая база. Первая глава включают в себя обзор иностранной и отечественной литературы по теме исследования. В ней описаны специфика спортивной деятельности, профессионально-важные качества спортсменов к изучению личностных особенностей спортсменов. Выводы по первой главе представляют собой итоги по изучению теоретического материала. Вторая глава посвящена эмпирической части исследования. В ней представлено описание организации и методов проведенного исследования и результатов, полученных по всем использованным методикам: -методика диагностики личности на мотивацию к успеху Т. Элерса; - шкала личностной и ситуативной тревожности Ч. Д. Спилберга - Ю. Л. Ханина; - опросник уровня субъективного контроля (УСК) Дж. Роттера; - опросник «Оценка уровня притязаний» В. К. Гербачевского; - тест-опросник А.В. Зверькова и Е.В. Эйдмана «Исследование волевой саморегуляции». Выводы по главе 2 включают в себя основные результаты эмпирического исследования. В заключении в обобщенном виде изложены результаты теоретической и эмпирической частей работы, а также выводы по выдвинутым гипотезам, обоснована практическая значимость исследования.
586

Тематическая группа «напитки» в русском и китайском языках : магистерская диссертация / Theme group «drinks» in Russian and Chinese

Чэнь, Ш., Chen, S. January 2019 (has links)
Магистерская диссертация углубляет современные научные представления о содержании тематической группы «напитки». Исследование представляет собой опыт сопоставительного анализа лексических единиц русского и китайского языков, входящих в тематическую группу «напитки». Исследуемая тематическая группа «напитки» представлена тематическими подгруппами «алкогольные напитки» и «безалкогольные напитки». Были выделены лексем, которые являются культурно-специфическими для каждого из исследуемых языков. / The master’s thesis sheds light on the modern scientific views on the content of the themе group «drinks». The study is an experience of comparative analysis of lexical units of Russian and Chinese languages included in the themе group «drinks». The studied themе group «drinks» is represented by themе subgroups «strong drinks» and «soft drinks». Lexemes that are culturally specific for each of the studied languages were identified.
587

Limit theorems for rare events in stochastic topology

Zifu Wei (15420086) 02 December 2023 (has links)
<p>This dissertation establishes a variety of limit theorems pertaining to rare events in stochastic topology, exploiting probabilistic methods to study simplicial complex models. We focus on the filtration of \vc ech complexes and examine the asymptotic behavior of two topological functionals: the Betti numbers and critical faces. The filtration involves a parameter rn>0 that determines the growth rate of underlying Cech complexes. If rn depends also on the time parameter t, the obtained limit theorems will be established in a functional sense.</p> <p>The first part of this dissertation is devoted to investigating the layered structure of topological complexity in the tail of a probability distribution. We establish the functional strong law of large numbers for Betti numbers, a basic quantifier of algebraic topology, of a geometric complex outside an open ball of radius Rn, such that Rn to infinity as the sample size n increases. The nature of the obtained law of large numbers is determined by the decay rate of a probability density. It especially depends on whether the tail of a density decays at a regularly varying rate or an exponentially decaying rate. The nature of the limit theorem depends also on how rapidly Rn diverges. In particular, if Rn diverges sufficiently slowly, the limiting function in the law of large numbers is crucially affected by the emergence of arbitrarily large connected components supporting topological cycles in the limit.</p> <p>The second part of this dissertation investigates convergence of point processes associated with critical faces for a Cech filtration built over a homogeneous Poisson point process in the d-dimensional flat torus. The convergence of our point process is established in terms of the  Mo-topology, when the connecting radius of a Cech complex decays to 0, so slowly that critical faces are even less likely to occur than those in the regime of threshold for homological connectivity. We also obtain a series of limit theorems for positive and negative critical faces, all of which are considerably analogous to those for critical faces.</p>
588

[pt] UNICIDADE DE SOLUÇÕES LP-FORTES / [en] UNIQUENESS OF LP-STRONG SOLUTIONS

GABRIEL GOMES FIGUEIREDO 26 September 2023 (has links)
[pt] Esta dissertação de mestrado aborda um estudo aprofundado do artigo [2]. No Capítulo 2, são introduzidas as definições e conceitos fundamentais necessários para a análise teórica subsequente. Uma proposição é demonstrada, estabelecendo a existência de uma expansão de Taylor para funções em um determinado espaço, enfatizando o papel do expoente de Escauriaza. O capítulo continua apresentando dois lemas que relacionam subsoluções e supersoluções em termos de viscosidade e propriedades de normas. A primeira versão do lema considera a relação entre a dimensão do espaço e a norma, enquanto a segunda versão utiliza o expoente de Escauriaza para obter resultados mais refinados. Também são apresentados dois resultados que explicam a relação entre diferentes noções de soluções viscosas e sua conexão com os espaços de Sobolev. As propriedades dos operadores de Pucci são discutidas como conclusão deste capítulo. No Capítulo 3, a dissertação estabelece a definição da geometria da fronteira do domínio em questão. Em seguida, um importante lema é demonstrado, estabelecendo a existência de soluções fortes em um determinado espaço, explorando a regularidade das funções envolvidas com base nesse lema. Os conceitos de super-diferenciabilidade e sub-diferenciabilidade são introduzidos, desempenhando um papel crucial na compreensão do comportamento das soluções viscosas e suas relações com derivadas de ordem superior. Um resultado geral que amplia essas definições é apresentado. Duas versões em que a função u é duas vezes super-diferenciável são discutidas, considerando o espaço Ld e posteriormente o espaço Lp , de modo que p menor que d. A dissertação prossegue demonstrando a relação entre sub-solução Lp-viscosidade e sub-solução Lp-forte quando u pertence a um espaço específico. Em seguida, é mostrado que os limites uniformes de soluções também são soluções. Por fim, é apresentado o resultado principal da dissertação, demonstrando a unicidade das soluções fortes. / [en] This master s thesis delves into an in-depth study of the article [2]. Chapter2 begins by introducing fundamental definitions and concepts essential forthe subsequent theoretical analysis. A proposition is then demonstrated,establishing the existence of a Taylor expansion for functions in a givenspace, emphasizing the role of the Escauriaza exponent.The chapter proceeds to present two lemmas that relate subsolutions andsupersolutions in terms of viscosity and properties of norms. The firstversion of the lemma considers the relationship between the dimension ofspace and the norm, while the second version uses the Escauriaza exponentto obtain more refined results. Two results are shown to explain that explainthe relationship between different notions of viscous solutions and theirconnection with Sobolev spaces.The properties of the Pucci operators are discussed at the conclusion of thischapter. Chapter 3 begins by establishing the definition of the boundarygeometry of the domain in question. An important lemma is demonstrated,which establishes the existence of strong solutions in a given space andexplores the regularity of the functions involved based on this lemma.The concepts of superdifferentiability and subdifferentiability areintroduced, playing a crucial role in understanding the behavior of viscoussolutions and their relationships with higher order derivatives. A generalresult that extends these definitions is presented. The dissertation discussestwo versions wherein the function u is twice super-differentiable, consideringthe space Ld and later the space Lp, so that p less than d.The dissertation goes on to demonstrate the relationship between Lp-viscosity sub-solution and Lp-strong sub-solution when u belongs to aspecific space. Next, it is shown that the uniform limits of solutions arealso solutions. Finally, the main result of the dissertation is presented,demonstrating the uniqueness of strong solutions.
589

Driving strong-field dynamics with tailored laser pulses

Bengs, Ulrich 15 May 2023 (has links)
Durch fortschreitende Entwicklung im Bereich der Starkfeldphysik und der Lasertechnologie in den letzten Jahrzehnten kann die Dynamik von Elektronen induziert durch Laserpulse verschiedener Wellenlängen, komplexen Polarisationseigenschaften, ultrakurzer Dauer und großer Intensität in hohem Umfang kontrolliert und ausgenutzt werden. In dieser Arbeit werden maßgeschneiderte Laserpulse angewendet, um verschiedene Aspekte der atomaren Licht-Materie-Wechselwirkung im Starkfeldbereich zu untersuchen. Im ersten Teil der Arbeit wird insbesondere die Erzeugung von hohen Harmonischen erforscht, die durch zirkular polarisierte Laserfelder erzeugt werden, wobei das maßgeschneiderte Feld aus einem zirkular polarisierten Infrarotpuls und seiner zweiten Harmonischen mit entgegengesetzter zirkularer Polarisation besteht. Die Polarisation von zirkularen hohen Harmonischen wird mittels spektral aufgelöster Polarimetrie unter Verwendung eines selbst entwickelten Polarimeters gemessen und ein Verfahren vorgestellt, mit dem der Stokes-Vektor der hoch zirkular polarisierten Harmonischen vollständig rekonstruiert werden kann. Darüber hinaus wird zum ersten Mal gezeigt, dass das bizirkulare Schema auch auf erzeugende Laserpulse weniger Zyklen erweiterbar ist. Der zweite Teil der Arbeit konzentriert sich auf die Starkfeldanregung eines Atoms durch einen intensiven Laserpuls. Da die ponderomotorische Verschiebung eines ausreichend intensiven Laserpulses eine resonante Anregung eines durch den Stark-Effekt verschobenen Atomzustands sowohl an der Vorder- als auch an der Rückflanke des Pulses bewirkt, diktiert die fundamentale Quantenmechanik, dass die an diesen Instanzen angeregten Elektronenwellenpakete interferieren müssen. Durch Variation der Verzögerung zwischen den Instanzen kann ein Interferenzmuster beobachtet werden, das als Stückelberg-Oszillationen bekannt ist und wertvolle Informationen über die Ionisierungsrate stark angeregter atomarer Zustände enthält. / As our fundamental understanding of strong-field physics and laser technology have matured in the last few decades, we are able to control and exploit electron dynamics using laser pulses of multiple colors, complex polarization properties, ultrashort duration and high intensity. This thesis makes use of such tailored laser fields to study different aspects of atomic light-matter interaction within the strong-field regime. Particularly, the first part of the thesis explores high-harmonic generation driven by circularly polarized driving fields, where the tailored field is composed of a circularly polarized infrared pulse and its second harmonic with opposite circular polarization, often denoted as 'bicircular' driving field. We measure the polarization of bicircularly generated harmonics by means of spectrally resolved polarimetry using a self-developed polarimeter and present a scheme, which allows to fully reconstruct the Stokes vector of the highly circularly polarized harmonics. We further demonstrate for the first time, that the bicircular scheme is also applicable within the regime of few-cycle driving pulses. Applying driving fields containing only a few carrier oscillations, we present the generation of a broadband harmonic spectrum with highly elliptically polarized spectral content, supporting the generation of an isolated attosecond pulse. The second part of the thesis focuses on strong-field excitation of an atom by an intense laser pulse. When the ponderomotive shift of a sufficiently intense laser pulse induces resonant excitation of a Stark-shifted atomic state at both the leading and trailing edge of the pulse, fundamental quantum mechanics dictates that the electron wave packets excited at these instances must interfere. By varying the delay between the instances, we observe the interference pattern known as Stückelberg oscillations which holds valuable information about the ionization rate of strongly driven atomic states.
590

Accélération du lentillage gravitationnel à plans multiples par apprentissage profond

Wilson, Charles 04 1900 (has links)
Le "modèle standard" actuel de la cosmologie est celui de ΛCDM, décrivant un Univers en expansion accélérée ainsi qu’une structure de matière sombre froide formée en halos, sur lesquels s’assemblent les galaxies. Malgré les nombreuses confirmations observationnelles de ses prédictions, il existe d’importantes tensions entre les mesures de la distribution de structure sombre aux petites échelles de l’Univers et ce qui serait attendu de ΛCDM. Cependant, ces halos légers de matière sombre, qui sont prédit d’abonder à travers le cosmos, n’hébergent pas de galaxies lumineuses et sont donc très difficiles à observer directement. Leur présence peut toutefois être détectée dans les lentilles gravitationnelles fortes de type galaxie-galaxie, un phénomène se produisant lorsque la lumière d’une galaxie d’arrière-plan est fortement déviée par le champ gravitationnel d’une galaxie d’avantplan, formant des images multiples et des arcs étendus. Les halos distribués en ligne de visée de tels systèmes, ainsi que ceux imbriqués dans la galaxie lentille, peuvent causer des perturbations gravitationnelles dans les images de galaxies lentillées. La détection de ces effets infimes dans des observations de lentilles gravitationnelles est faite par des méthodes statistiques Bayésiennes, qui nécéssitent des centaines de milliers de simulations de la contribution de ces perturbateurs à la déflexion de la lumière. Traditionnellement, la modélisation du lentillage par les halos en ligne de visée s’est faite avec le formalisme du lentillage à plans multiples, qui souffre d’une nature récursive peu efficace. De plus, il est prédit par le modèle ΛCDM que la majorité des systèmes de lentilles gravitationnelles comporteraient davantage de halos en ligne de visée que de sous-halos imbriqués dans la galaxie lentille, motivant une modélisation détaillée des effets de ligne de visée. Dans un contexte d’analyse Bayésienne, l’approche du lentillage à plans multiples représente une échelle de temps de plusieurs jours pour l’analyse d’un seul système. En considérant que des grands relevés du ciel comme ceux de l’Observatoire Vera Rubin et du télescope spatial Euclid sont projetés de découvrir des centaines de milliers de lentilles gravitationnelles, l’effort de contraindre la distribution de matière sombre aux petites échelles se voit confronté à ce qui pourrait être un insurmontable problème de temps de calcul. Dans ce mémoire, je présente le développement d’un nouveau formalisme de modélisation du lentillage gravitationnel par halos en ligne de visée accéléré par des réseaux de neurones, motivé par les lacunes du lentillage à plans multiples et l’importance scientifique de la modélisation de ces effets. Les architectures de ces réseaux, conçues dans le cadre de ce travail, sont basées sur le mécanisme d’attention, et peuvent être conditionnées sur des ensembles de modèles de halos en ligne de visée afin de produire les angles de déflexion leur étant associés. Ce formalisme offre la flexibilité requise pour remplacer celui du lentillage à plans multiples, laissant à l’usager la liberté de spécifier un modèle de lentille principale et étant compatible avec des grilles de pixels de taille quelconque. Notre formalisme permet d’accélérer la modélisation du lentillage de ligne de visée par presque deux ordres de grandeur lorsque comparé au lentillage à plans multiples, et promet d’atteindre une exactitude lui étant comparable dans des développements futurs. Il s’agit d’une contribution significative à l’étude de la matière sombre aux petites échelles, qui permettra soit de réconcilier ΛCDM et les observations, ou mènera à l’adoption d’un modèle cosmologique alternatif. / The current "standard model" of cosmology is that of ΛCDM, describing a Universe undergoing accelerated expansion with a structure of cold dark matter formed into halos, onto which are assembled galaxies. Despite the numerous observational confirmations of its predictions, there remains some important tensions between measures of the distribution of dark structure on small scales of the Universe and what would be expected from ΛCDM. However, these light dark matter halos, predicted to be adundant throughout the cosmos, are not hosts of luminous galaxies and are therefore very difficult to observe directly. Yet, their presence can still be detected in galaxy-galaxy type strong gravitational lenses, a phenomenon occuring when the light of a background galaxy is strongly deflected by the gravitational field of a foreground galaxy, forming multiple images and extended arcs. Halos distributed along the line-of-sight of such systems, as well as those nested within the lens galaxy, can introduce gravitational perturbations in images of lensed galaxies. The detection of such infinitesimal effects in strong lensing observations is made with methods relying on Bayesian statistics, which require hundreds of thousands of simulations of the contribution of these perturbers to the deflection of light. Traditionally, modeling the lensing from line-of-sight halos has been done with the multi-plane lensing framework, which suffers from its inefficient recursive nature. Morevoer, the ΛCDM model predicts that most gravitational lens systems would host a larger amount of line-of-sight halos than subhalos nested within the lens galaxy, motivating a detailed modeling of line-of-sight effects. In a Bayesian analysis context, the multi-plane lensing approach represents a timescale of multiple days for the analysis of a single system. Considering that large sky surveys such as those of the Vera Rubin Observatory and the Euclid space telescope are projected to discover hundreds of thousands of gravitational lenses, the effort of constraining the small-scale distribution of dark matter is confronted to what might seem like an insurmountable problem of computation time. In this thesis, I present the development of a new neural-network-accelerated framework for modeling the gravitational lensing by line-of-sight halos, motivated by the shortcomings of multiplane lensing and the scientific importance of modeling these effects. The architectures of these networks, conceived as part of this work, are based on the attention mechanism, and can be conditioned on sets of line-of-sight halo models in order to produce their associated deflection angles. This framework offers the flexibility required to replace that of multi-plane lensing, leaving up to the user the freedom to specify a main lens model and being compatible with pixel grids of any size. Our framework allows to accelerate the modeling of line-of-sight lensing by nearly two orders of magnitude relative to multi-plane lensing, and promises to reach a comparable accuracy in future developments. This constitutes a significative contribution to the study of dark matter on small scales, which will either lead to the reconciliation of ΛCDM and observations, or the adoption of an alternate cosmological model.

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