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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.
41

Stabilitätsuntersuchungen an Asteroidenbahnen in ausgewählten Bahnresonanzen des Edgeworth-Kuiper-Gürtels

Gerlach, Enrico 14 November 2008 (has links) (PDF)
Gegenstand dieser Dissertation ist eine umfassende Analyse der Stabilität von Asteroidenbahnen im Edgeworth-Kuiper-Gürtel am Beispiel der 3:5-, 4:7- und der 1:2-Bahnresonanz mit Neptun. Einen weiteren Schwerpunkt der Arbeit bildet die Untersuchung der numerischen Berechenbarkeit der Lyapunov-Zeit von Asteroidenbahnen. Ausgehend von einer allgemeinen Beschreibung der bei numerischen Berechnungen auftretenden Rundungs- und Diskretisierungsfehler wird deren Wachstum bei numerischen Integrationen ermittelt. Diese, teilweise maschinenabhängigen, Fehler beeinflussen die berechnete Trajektorie des Asteroiden ebenso wie die daraus abgeleitete Lyapunov-Zeit. Durch Beispielrechnungen mit unterschiedlichen Rechnerarchitekturen und Integrationsmethoden wird der Einfluss auf die erhaltenen Lyapunov-Zeiten eingehend untersucht. Als Maß zur Beschreibung dieser Abhängigkeit wird ein Berechenbarkeitsindex $\kappa$ definiert. Weiterhin wird gezeigt, dass die allgemeine Struktur des Phasenraumes robust gegenüber diesen Änderungen ist. Unter Nutzung dieser Erkenntnis werden anschließend ausgewählte Bahnresonanzen im Edgeworth-Kuiper-Gürtel untersucht. Grundlegende Charakteristika, wie die Resonanzbreiten, werden dabei aus einfachen Modellen abgeleitet. Eine möglichst realitätsnahe Beschreibung der Stabilität wird durch numerische Integration einer Vielzahl von Testkörpern zusammen mit den Planeten Jupiter bis Neptun erreicht. Die erhaltenen Ergebnisse werden dabei mit der beobachteten Verteilung der Asteroiden im Edgeworth-Kuiper-Gürtel verglichen. ---- Hinweis: Beim Betrachten der pdf-Version dieses Dokumentes mit dem Acrobat Reader mit einer Version kleiner 8.0 kann es unter Windows zu Problemen in der Darstellung der Abbildungen auf den Seiten 46, 72, 74, 79 und 86 kommen. Um die Datenpunkte zu sehen ist eine Vergrößerung von mehr als 800% notwendig. Alternativ kann in den Grundeinstellungen der Haken für das Glätten von Vektorgraphiken entfernt werden. / This dissertation presents a comprehensive description of the stability of asteroid orbits in the Edgeworth-Kuiper belt taking the 3:5, 4:7 and 1:2 mean motion resonance with Neptune as example. Further emphasis is given to the numerical computability of the Lyapunov time of asteroids. Starting with a general description of rounding and approximation errors in numerical computations, the growth of these errors within numerical integrations is estimated. These, partly machine-dependent errors influence the calculated trajectory of the asteroid as well as the derived Lyapunov time. Different hardware architectures and integration methods were used to investigate the influence on the computed Lyapunov time. As a measure of this dependence a computability index $\kappa$ is defined. Furthermore it is shown, that the general structure of phase space is robust against these changes. Subsequently, several selected mean motion resonances in the Edgeworth-Kuiper belt are investigated using these findings. Basic properties, like the resonance width, are deduced from simple models. To get a realistic description of the stability, a huge number of test particles was numerically integrated together with the planets Jupiter to Neptune. The obtained results are compared to the observed distribution of asteroids in the Edgeworth-Kuiper belt. ---- Additional information: If the pdf-file of this document is viewed using Acrobat Reader with a version less 8.0 under Windows the figures on page 46, 72, 74, 79 and 86 are shown incomplete. To see the data points a zoom factor larger than 800% is necessary. Alternatively the smoothing of vector graphics should be disabled in the settings of the reader.
42

Stabilitätsuntersuchungen an Asteroidenbahnen in ausgewählten Bahnresonanzen des Edgeworth-Kuiper-Gürtels

Gerlach, Enrico 24 October 2008 (has links)
Gegenstand dieser Dissertation ist eine umfassende Analyse der Stabilität von Asteroidenbahnen im Edgeworth-Kuiper-Gürtel am Beispiel der 3:5-, 4:7- und der 1:2-Bahnresonanz mit Neptun. Einen weiteren Schwerpunkt der Arbeit bildet die Untersuchung der numerischen Berechenbarkeit der Lyapunov-Zeit von Asteroidenbahnen. Ausgehend von einer allgemeinen Beschreibung der bei numerischen Berechnungen auftretenden Rundungs- und Diskretisierungsfehler wird deren Wachstum bei numerischen Integrationen ermittelt. Diese, teilweise maschinenabhängigen, Fehler beeinflussen die berechnete Trajektorie des Asteroiden ebenso wie die daraus abgeleitete Lyapunov-Zeit. Durch Beispielrechnungen mit unterschiedlichen Rechnerarchitekturen und Integrationsmethoden wird der Einfluss auf die erhaltenen Lyapunov-Zeiten eingehend untersucht. Als Maß zur Beschreibung dieser Abhängigkeit wird ein Berechenbarkeitsindex $\kappa$ definiert. Weiterhin wird gezeigt, dass die allgemeine Struktur des Phasenraumes robust gegenüber diesen Änderungen ist. Unter Nutzung dieser Erkenntnis werden anschließend ausgewählte Bahnresonanzen im Edgeworth-Kuiper-Gürtel untersucht. Grundlegende Charakteristika, wie die Resonanzbreiten, werden dabei aus einfachen Modellen abgeleitet. Eine möglichst realitätsnahe Beschreibung der Stabilität wird durch numerische Integration einer Vielzahl von Testkörpern zusammen mit den Planeten Jupiter bis Neptun erreicht. Die erhaltenen Ergebnisse werden dabei mit der beobachteten Verteilung der Asteroiden im Edgeworth-Kuiper-Gürtel verglichen. ---- Hinweis: Beim Betrachten der pdf-Version dieses Dokumentes mit dem Acrobat Reader mit einer Version kleiner 8.0 kann es unter Windows zu Problemen in der Darstellung der Abbildungen auf den Seiten 46, 72, 74, 79 und 86 kommen. Um die Datenpunkte zu sehen ist eine Vergrößerung von mehr als 800% notwendig. Alternativ kann in den Grundeinstellungen der Haken für das Glätten von Vektorgraphiken entfernt werden. / This dissertation presents a comprehensive description of the stability of asteroid orbits in the Edgeworth-Kuiper belt taking the 3:5, 4:7 and 1:2 mean motion resonance with Neptune as example. Further emphasis is given to the numerical computability of the Lyapunov time of asteroids. Starting with a general description of rounding and approximation errors in numerical computations, the growth of these errors within numerical integrations is estimated. These, partly machine-dependent errors influence the calculated trajectory of the asteroid as well as the derived Lyapunov time. Different hardware architectures and integration methods were used to investigate the influence on the computed Lyapunov time. As a measure of this dependence a computability index $\kappa$ is defined. Furthermore it is shown, that the general structure of phase space is robust against these changes. Subsequently, several selected mean motion resonances in the Edgeworth-Kuiper belt are investigated using these findings. Basic properties, like the resonance width, are deduced from simple models. To get a realistic description of the stability, a huge number of test particles was numerically integrated together with the planets Jupiter to Neptune. The obtained results are compared to the observed distribution of asteroids in the Edgeworth-Kuiper belt. ---- Additional information: If the pdf-file of this document is viewed using Acrobat Reader with a version less 8.0 under Windows the figures on page 46, 72, 74, 79 and 86 are shown incomplete. To see the data points a zoom factor larger than 800% is necessary. Alternatively the smoothing of vector graphics should be disabled in the settings of the reader.
43

Estimations précises de grandes déviations et applications à la statistique des séquences biologiques

Pudlo, Pierre 16 December 2004 (has links) (PDF)
Pour obtenir des listes de mots de fréquences exceptionnelles par rapport à un modèle aléatoire, par exemple dans un contexte de biologie moléculaire, il faut quantifier la qualité de la prédiction des fréquences d'une famille de mots. Nous étudions les probabilités de grandes déviations du processus vectoriel de comptage d'une famille de mots dans des modèles de Markov et des modèles de Markov cachés. Pour démontrer ces résultats, nous établissont un développement du type Edgeworth sur les fonctionnelles additives d'une chaîne de Markov finie. Nous utilisons les théorèmes obtenus pour produire des listes de mots exceptionnels dans les génomes d'Escherichia Coli et de Bacillus Subtilis par conditionnements successifs d'un modèle statistique initial.
44

Pozicinių statistikų tiesinių kombinacijų skirstinių aproksimacijos baigtinėse populiacijose / Approximations to distributions of linear combinations of order statistics in finite populations

Čiginas, Andrius 31 January 2012 (has links)
Disertacijoje tiriamos negrąžintinių imčių pozicinių statistikų tiesinių kombinacijų (L-statistikų) savybės. Pagrindinis disertacijos uždavinys yra L-statistikų skirstinių normaliosios aproksimacijos patikslinimas trumpaisiais Edgeworth'o skleidiniais. Šių aproksimacijų tikslumui įvertinti disertacijoje naudojamas baigtinių populiacijų simetrinių statistikų Hoeffding'o skleidinys. Pirmame disertacijos skyriuje gautos išreikštinės pirmųjų L-statistikos Hoeffding'o skleidinio narių ir skleidinio liekamųjų narių formulės. Jomis naudojantis, antrame disertacijos skyriuje išspręsti tokie uždaviniai: gautas optimalus imties ekstremaliųjų reikšmių dispersijų viršutinysis įvertis; nustatytos pakankamosios L-statistikų asimptotinio normalumo sąlygos; sukonstruotas trumpasis L-statistikos Edgeworth'o skleidinys ir nustatytos pakankamosios šios aproksimacijos sąlygos. Trečiame disertacijos skyriuje sukonstruoti L-statistikos dispersijos ir Edgeworth'o skleidinio parametrų įvertiniai. Ketvirtame disertacijos skyriuje sukonstruoti ir ištirti Stjudentizuotų ir kartotinių imčių L-statistikų trumpieji Edgeworth'o skleidiniai. / Properties of linear combinations of order statistics (L-statistics), where samples are drawn without replacement, are considered in the thesis. The main object of the thesis is an improvement of the normal approximation to distributions of L-statistics by one-term Edgeworth expansions. An accuracy of these approximations is estimated using the Hoeffding decomposition of finite population symmetric statistics. In the first chapter of the thesis, explicit expressions of the first terms and remainder terms of the Hoeffding decomposition of L-statistics are obtained. The main applications of the decomposition are given in the second chapter: the optimal upper bound for variances of the sample minimum and maximum is obtained; sufficient conditions for the asymptotic normality of L-statistics are established; the one-term Edgeworth expansion for L-statistics is constructed and sufficient conditions for the validity of this approximation are obtained. In the third chapter, estimators of the variance and parameters that define the Edgeworth expansion of an L-statistic are constructed. In the fourth chapter, a one-term Edgeworth expansion for a Studentized L-statistic and empirical Edgeworth expansions are constructed and analyzed.
45

Approximation stochastischer Charakteristiken von Funktionalen schwach korrelierter Prozesse / Approximation of stochastic characteristics of functionals of weakly correlated random processes

Ilzig, Katrin 09 July 2010 (has links) (PDF)
In praktischen Aufgabenstellungen können zur Modellierung zufälliger Einflüsse, welche sich durch schwache Abhängigkeiten auszeichnen, schwach korrelierte zufällige Funktionen genutzt werden. Die nähere Untersuchung von Funktionalen schwach korrelierter zufälliger Funktionen ist durch die Gestalt der Lösungen von praktischen Fragestellungen motiviert. Die stochastischen Charakteristiken dieser Lösungen lassen sich im Allgemeinen nicht exakt bestimmen, so dass auf Approximationsverfahren zurückgegriffen werden muss. Diese stehen im Mittelpunkt der Dissertation. Zu Beginn werden Entwicklungen von Momenten und Kumulanten der betrachteten linearen Integralfunktionale schwach korrelierter Prozesse nach der Korrelationslänge des Prozesses hergeleitet und eine Vermutung über die exakte Darstellung der Kumulanten formuliert. Für Integralfunktionale von schwach korrelierten Simulationsprozessen, welche aus der Interpolation von Moving-Average-Prozessen entstehen, werden die definierten Charakteristiken hergeleitet. Außerdem steht die Approximation der unbekannten Dichtefunktion im Fokus der Arbeit. Es werden verschiedene Zugänge genutzt. Eine alternative Herleitung zur bereits in der Literatur untersuchten Gram-Charlier-Entwicklung wird in Form der Edgeworth-Entwicklung angegeben. Des Weiteren werden die Sattelpunkt-Approximation und die Maximum-Entropie-Methode untersucht und anhand von Simulationsergebnissen für Integralfunktionale von Simulationsprozessen miteinander verglichen. / In engineering applications stochastic influences which are characterized by weak dependencies can be modelled, among others, by weakly correlated random functions. The solutions of such problems shape up as integral functionals of weakly correlated random functions which motivates more detailed investigations. In general the exact calculation of stochastic characteristics of such integral functionals is impossible so that we have to be content with approximation methods this thesis focuses on. At the beginning expansions of moments and cumulants of linear integral functionals of weakly correlated random processes with respect to the correlation length are considered and an explicit formula of cumulants is conjectured. For integral functionals of weakly correlated random simulation processes, defined as interpolations of moving average processes, the required expansion coefficients are derived. Furthermore the approximation of the unknown probability density is requested. In the thesis there are different approaches used. First we state an alternative way to achieve the already known Gram Charlier approximation by means of Edgeworth expansion. Then we study two further methods, namely the saddlepoint approximation and the maximum entropy method and compare them on the basis of simulation results for integral functionals of simulation processes.
46

The "Improperly Educated" Woman in British Novels, 1790-1801

Osbourne, Lacie 2012 August 1900 (has links)
This dissertation identifies the character type of the "improperly educated" woman, who is both rationally educated and passionately outspoken, and examines the delineation of this recurring figure, in relation to the female education continuum, within the evolving discourse on female learning during the period of 1790-1801. British women writers, who opposed the deficient education offered to females, contributed their voices to collectively challenging the notion that education deprived the female sex of their femininity. Consequently, women novelists exploited the "improperly educated" female character as a means to explore alternatives to the existing curriculum, specifically rational and classical knowledge and to consider the negative effects of restrictive gender identities on female education. I employ feminist literary history and criticism to evaluate the participation of Elizabeth Inchbald, Mary Hays, and Maria Edgeworth in this continuing educational debate through their advocation for restructuring of the educational system and their effective use of versions of the "improperly educated" woman to portray women as intellectually capable. Challenging the conception of "feminine" as a natural state, Inchbald, Hays, and Edgeworth used fictional narratives to show the difficulties of strict adherence to proper femininity and to portray the irony of an education that does not enlighten but rather restricts and censors. Inchbald's A Simple Story, Hays' Memoirs of Emma Courtney, and Edgeworth's Belinda respectively demonstrate the important role played by this character type in regards to eighteenth and early nineteenth-century women writers' efforts to promote improvements in female instruction, encourage female autonomy, and demonstrate women's capabilities for self-improvement. Undeterred by traditional custom, women novelists renewed literary efforts to display similarities between women of diverse social classes and levels of learning, thus exposing the adverse consequences of the conventionally transitory and inferior education, which the majority of the female sex experienced. This character makes a significant impact in promoting improvement in the educational system and revising the definition of proper feminine behavior within British society.
47

Reinventing Virtue: Sensibility and Sentiment in the Works of Maria Edgeworth

Sawyer, Octavia Cathryn 18 March 2009 (has links) (PDF)
While literary scholars have written extensively about sensibility in the past two decades, most of the studies have treated either the history of sensibility itself or how it interacted with a particular aspect of English culture and literature, such as sexuality or politics. My project instead examines how a single author, Maria Edgeworth, used sensibility in her writing over the course of her career. I analyze the use of sensibility in three of her novels: Belinda (1801), her first full-length novel; The Absentee (1812), her influential Irish national tale, written at the height of her popularity in the middle years of her career; and Helen (1834), her last novel. This analysis illustrates the changing attitude of both Edgeworth and English society to sensibility and its representations in literature. In Belinda, Edgeworth uses sensibility to demonstrate the virtue and superiority of the characters who possess it, and also to rehabilitate the concept itself. She differentiates between mere affectation and true sensibility by creating both positive and negative examples of sensibility in Belinda – characters clearly possess true sensibility, and those who only pretend to it. In The Absentee, Edgeworth adheres much more closely to the conventions of sentimental fiction than she had in her previous society novels. In my discussion of The Absentee, I demonstrate how Edgeworth uses the conventions of sentiment both to make Irish culture accessible to her English audience and to justify the Irish estate system which put Anglo-Irish landowners in a position of authority over native Irish tenants. My final section focuses on Edgeworth's last novel, Helen, which marks a return to the genre of the society novel with which she began her career. While Edgeworth still uses sensibility as a sign of virtue in Helen, she is also much more interested than previously in the interplay between education and inborn qualities of personality – the very qualities whose existence she was so skeptical of in her education manual, Practical Education, published two years before she began her career as a fiction writer.
48

Serving the Storyline of the Novel: The Powerful Role of the Feudal Servant-Narrator

Turner, Stephanie 01 May 2009 (has links)
This thesis addresses issues of class as represented through the narrative agency exercised by the servant-narrator in Castle Rackrent and Wuthering Heights. Thady Quirk and Ellen Dean are servant-narrators who strategically use feigned allegiance, astute perception, and selective disclosure to wield power over the lives of their masters. These “arts of subordination” allow the servant-narrator to tell his or her own life narrative, while appearing to share the masters’ memoirs. While both servant-narrators are motivated by economic means, Ellen Dean’s involvement throughout Wuthering Heights is further complicated by her desires of emotional connection. However, each servant-narrator achieves his or her goals by manipulating the events and relationships that constitute his or her masters’ lives.
49

Romantic peripheries: the national subject and the colonial bildungsroman in Edgeworth, Scott, Child and Hogg

Shannon, Ashley Elizabeth 28 August 2008 (has links)
Not available / text
50

Mimicry, Imitation, and Double Consciousness: The Absence and Presence of Black Heroines in The Woman of Colour and William Earle's Obi

Bezanson, Brianne 19 August 2013 (has links)
This thesis demonstrates how two early nineteenth century British novels, William Earle’s Obi, or The History of Three-Fingered Jack (1800) and the anonymously-written The Woman of Colour; A Tale (1808), feature prominent women of colour that move beyond the silenced, enslaved, minor representations of black and mixed race women made popular in previously published texts throughout the seventeenth and eighteenth centuries. The progression of Amri and Olivia’s positions through the use of literary strategies, such as Homi K. Bhabha’s mimicry, Paul Gilroy’s double consciousness, and gender-reversals reveal the inherent ambivalence of the women’s positions in each narrative and the importance of these representations against the hegemonic female position. Although I argue that neither author succeeds in overturning traditional limitations of representing women of colour in literature of the period, investigating these texts is crucial to understanding the autonomous, influential women of colour in later nineteenth century literary works.

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