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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.
541

Qualitative Analysis of Solutions to the Semiclassical Einstein Equation in homogeneous and isotropic Spacetimes

Hänsel, Mathias 07 January 2019 (has links)
In der vorliegenden Arbeit werden Methoden aus der Theorie der dynamischen Systeme verwendet, um das qualitative Verhalten von Lösungen der semiklassischen Einsteingleichung für Friedmann-Lamaître-Robertson-Walker Raumzeiten zu untersuchen. Es werden ausschließlich masselose und konform gekoppelte Quantenfelder betrachtet. Bei der Renormierung des Energie-Impuls-Tensors solcher Quantenfelder treten Ambiguitäten auf, die sich als freie Parameter in der semiklassischen Einsteingleichung manifestieren. Mit Hilfe der Theorie der dynamischen Systeme ist es möglich, Lösungen nach ihren qualitativen Verhalten zu klassifizieren und dadurch Argumente für oder gegen bestimmte Werte der Renormierungskonstanten herauszuarbeiten. Befindet sich das Quantenfeld im konformen Vakuumzustand, erhält man ein zweidimensionales dynamisches System. Für dieses dynamische System werden die strukturell stabilen Fälle und Bifurkationsdiagramme herausgearbeitet, sowie das globale Stabilitätsverhalten der Minkowski und De-Sitter Gleichgewichtspunkte. Mittels dieser Analyse wird das qualitative Verhalten der semiklassischenLösungen mit dem qualitativen Verhalten der Lösungen des Lambda-CDM Modells der Kosmologie verglichen. Es zeigt sich, dass das semiklassische Modell in der Lage ist das qualitative Verhalten von Lösungen des klassischen Lambda-CDM Modells wiederzugeben. Weiterhin wird gezeigt, das im Vakuumfall Lösungen existieren, welche sich, im Gegensatz zu Lösungen des klassischen Lambda-CDM Modells, im Allgemeinen nicht eindeutig durch ihre Anfangsdaten bestimmen lassen. Um dieses atypische Verhalten aufzulösen müssen die Trajektorien dieser Lösungen in einem dreidimensionalen Phasenraum betrachtet werden.Das entsprechende dreidimensionale dynamische System beschreibt das dynamische Verhalten der Lösungen für beliebige Quantenzustände. Für allgemeine Quantenzustände wird die lokale (Lyapunov-) Stabilität der Gleichgewichtspunkte untersucht und für eine spezielle Wahl der Renormierungskonstanten und des Quantenzustandes neue Lösungen gefunden und mit Lösungen des klassischen Lambda-CDM Modells verglichen. Auch hier besteht eine qualitative Äquivalenz.
542

'...and one of time.': A Composition for Full Orchestra with Narration

Rinker, John Thomas 12 1900 (has links)
‘...and one of time.' is a reinterpretation of a small musical moment from Philip Glass' opera, Einstein on the Beach, centered around the phrase "Berne, Switzerland 1905." This reinterpretation is realized through the use of several different compositional techniques including spectral composition, micropolyphony and dodecaphony, as well as the application of extra-musical models developed by Alan Lightman, John Gardner, Italo Calvino and Albert Einstein.
543

The Total Acquisition Number of the Randomly Weighted Path

Godbole, Anant, Kelley, Elizabeth, Kurtz, Emily, Pralat, Pawel, Zhang, Yiguang 01 January 2017 (has links)
There exists a significant body of work on determining the acquisition number at(G) of various graphs when the vertices of those graphs are each initially assigned a unit weight. We determine properties of the acquisition number of the path, star, complete, complete bipartite, cycle, and wheel graphs for variations on this initial weighting scheme, with the majority of our work focusing on the expected acquisition number of randomly weighted graphs. In particular, we bound the expected acquisition number E(at(Pn)) of the n-path when n distinguishable "units" of integral weight, or chips, are randomly distributed across its vertices between 0.242n and 0.375n. With computer support, we improve it by showing that E(at(Pn)) lies between 0.29523n and 0.29576n. We then use subadditivity to show that the limiting ratio lim E(at(Pn))/n exists, and simulations reveal more exactly what the limiting value equals. The Hoeffding-Azuma inequality is used to prove that the acquisition number is tightly concentrated around its expected value. Additionally, in a different context, we offer a non-optimal acquisition protocol algorithm for the randomly weighted path and exactly compute the expected size of the resultant residual set.
544

Cation and Anion Transport in a Dicationic Imidazolium-Based Plastic Crystal Ion Conductor

Kidd, Bryce Edwin 10 July 2013 (has links)
Here we investigate the organic ionic plastic crystal (OIPC) 1,2-bis[N-(N\'-hexylimidazolium-d2(4,5))]C2H4 2PF6- in one of its solid plastic crystal phases by means of multi-nuclear solid-state (SS) NMR and pulsed-field-gradient (PFG) NMR. We quantify distinct cation and anion diffusion coefficients as well as the diffusion activation energies (Ea) in this dicationic imidazolium-based OIPC. Our studies suggest a change in transport mechanism for the cation upon varying thermal and magnetic treatment (9.4 T), evidenced by changes in cation and anion Ea. Moreover, variable temperature 2H SSNMR lineshapes further support a change in local molecular environment upon slow cooling in B0. Additionally, we quantify the percentage of mobile anions as a function of temperature from variable temperature 19F SSNMR, where two distinct spectral features are present. We also comment on the pre-exponential factor (D0), giving insight into the number of degrees of freedom for both cation and anion as a function of thermal treatment. In conjunction with previously reported conductivity values for this class of OIPCs and the Stokes-Einstein relation, we propose that ion conduction is dominated by anion diffusion between crystallites (i.e., grain boundaries). Using our experimentally determine diffusion coefficient and previously reported PF6- hydrodynamic radius (rH), viscous (" = 4.1 Pa " s) ionic liquid (IL) is present with a cation rH of 0.34 nm. NMR measurements are very powerful in elucidating fundamental OIPC properties and allow a deeper understanding of ion transport within such materials. / Master of Science
545

Production of Quantum Degenerate Mixtures of Alkali and Alkaline-Earth-Like Atoms / アルカリ原子とアルカリ土類様原子の量子縮退混合系の生成

Hara, Hideaki 23 January 2014 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第17973号 / 理博第3917号 / 新制||理||1565(附属図書館) / 80817 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 高橋 義朗, 教授 田中 耕一郎, 教授 石田 憲二 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
546

Non-Equilibrium Quantum Spin Transport Theory Based on Schwinger-Keldysh Formalism / Schwinger-Keldysh形式に基づく非平衡量子スピン輸送理論

Nakata, Kouki 24 March 2014 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18056号 / 理博第3934号 / 新制||理||1567(附属図書館) / 30914 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 戸塚 圭介, 教授 石田 憲二, 教授 川上 則雄 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
547

Parametric instabilities of the Yang-Mills field and far-from-equilibrium dynamics of overpopulated bosons / ヤン・ミルズ場のパラメトリック不安定性と過占有ボソン系の非平衡ダイナミクス

Tsutsui, Shoichiro 23 March 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20173号 / 理博第4258号 / 新制||理||1612(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 大西 明, 教授 國廣 悌二, 教授 川合 光 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
548

Preparation and Fast Quantum Control of 87Rb Bose-Einstein Condensates

Vithanage, Denuwan Kaushalya Attiligoda 31 July 2020 (has links)
No description available.
549

Breakdown of the Stokes-Einstein relation for nanoparticles

Baer, Andreas, Miličević, Zoran, Smith, David M., Smith, Ana-Sunčana 13 July 2022 (has links)
No description available.
550

Charged, Rotating Black Holes in Higher Dimensions

Verhaaren, Christopher Bruce 13 July 2010 (has links) (PDF)
We present a method for solving the Einstein-Maxwell equations in a five dimensional, asymptotically flat, black hole spacetime with three commuting Killing vector fields. In particular, we show that by reducing the dimension of the Einstein-Maxwell equations in a Kaluza-Klein like manner we can determine the components of the metric and vector potential which lie in the direction of the Killing vector fields. These components are determined by nine scalar fields each of which satisfy a partial differential equation in two variables. These equations take the form of an elliptic operator set equal to a nonlinear source. We find evidence that particular combinations of these fields satisfy Dirichlet boundary conditions, and are well suited to numerical solution using Green functions. Using this method we generate numerical solutions to the 4+1 Einstein-Maxwell equations corresponding to charged generalizations of the Myers-Perry solution. We also discover symmetry relations among the scalar equations which constrain their functional forms and posit the existence of two rigidity-theorem-like relations for electrovac spacetimes and sketch how their use generalizes our method to N+1 dimensions.

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