Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xi, 110 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 105-110).

Thesis (Ph. D.)--University of Chicago, 1914. / "Asher" on the t.p. is in Hebrew characters. Includes bibliographical references. Also available on the Internet.

University, Diss., 2000--Heidelberg.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Techn. University, Diss., 2004--Berlin.

Made available in DSpace on 2014-06-11T19:28:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-11Bitstream added on 2014-06-13T20:58:35Z : No. of bitstreams: 1 mazur_rl_me_guara.pdf: 2192483 bytes, checksum: 24772053abc0675fdf4455448fe4adc3 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / As superligas à base de níquel são aplicadas nos mais diversos e complexos sistemas de engenharia, entretanto há poucos dados sobre o comportamento erosivo destas superligas frente ao impacto de particulas sólidas em um fluxo gasoso. A erosão por partícula sólida é um fenômeno complexo e caracteriza-se pela deformação e remoção de material durante o impacto das partículas, gerando elevadas temperaturas. As superligas à base de níquel Nimonic 80 A e Inconel 600, são materiais que possuem ótimas propriedades mecânicas emelevadas temperaturas, por este motivo, as suas características quanto à erosão em temperatura ambiente, serão medidas e analisadas, em vista da perda das propriedades mecânicas dos aços em temperaturas mais altas durante o impacto das partículas. Os ensaios de erosão foram realizados em um dispositivo do tipo jato de impacto ar-areia, onde as partículas erosivas forma introduzidas em um sistema à alta pressão e aceleradas ao longo de um bocal antes de impactar a superfície do material, permitindo simular os principais parâmetros do desgaste erosivo. Os ensaios realizados apresentaram pequenas diferenças para todosângulos de impacto testados (15°, 30°, 60°, 90°), porém os intervalos de confiança se superpõem para quase todos eles apesar da marcante diferença entre as propriedades mecânicas das superligas Nimonic 80 A e Inconel 600, não sendo possível estabelecer alguma correlação com a resistência à erosâo. / The Ni-base superalloys are applied in several and complexest engineering systems, however there are few data about the erosive behaviour of these superalloys regarding the impact of solid particles in a gaseous flow. The solid particle erosion is a complex phenomenon and it is characerized by the deformation and material removal during the impact of the particles generating high temperatures. The Ni-basesuperalloys Nimonic 80 A and Inconel 600, have excellent mechanical properties in high temperature, by this reason, theirs characteristics in erosion at room temperature, will be measured and analyzed, in view of the losses of the mechanical properties of the steels in higher temperatures during the impact of the particles. The erosion tests have been performed in air-sand jet impingement device, where the erosive particles were introduced in a system with high pressure and accelerated along a nozzle before impact the surface of the material, allowing to simulate the main parameters of the erosion wear. The results showed small differences for all impact angles tested (15°, 30°, 60°, 90°), however the reliable intervals have been superimpsed for almost all of them, in spite of the great differences among the mechanical properties of the superalloys Nimonic 80 A and Inconel 600, it was noto possible to establish some correlation with the erosion resistance.

In the millennia of recorded human knowledge, no model for describing the workings of Nature is as elegant or complete as the Standard Model of Particle Physics (SM). However, the SM has several open questions and there exist multiple phenomena that it cannot explain. A pressing question is related to the mass of the Higgs boson, whose value the SM has no natural way of explaining, relying instead on the fine tuning of parameters to one part in 10^{28}. Many extensions of the SM propose new interactions and particles which solve this problem. A particularly common theme is that of new partners of the top quark, which in some models are fermionic and have vectorial couplings to the SM charged weak current. Such particles are referred to as vector-like quarks and represent a promising avenue of research. A search is presented for a vector-like quark with an exotic 5/3 charge (in units of the charge of the positron), referred to as an X5/3 particle. These particles are predicted in Composite Higgs theories, which rely on the masses of the X5/3 to be not more than ~2 TeV in order to solve the unnaturalness inherent in the mass of the Higgs boson. The search uses data collected by the CMS experiment in both 2015 and 2016 consisting of proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC. No significant excess of events is seen above the predicted background and limits are placed on the mass of the new top quark partner at 95% confidence level, excluding masses less than 1200 (1160) GeV for X5/3 particles that decay with right-handed (left-handed) couplings to W bosons. These are the most stringent limits to date on the mass of the X5/3 particle in this final state.

The sorption of caesium and strontium onto clay minerals by exchange with other, charge compensating cations was studied by batch experiments. It was demonstrated that, for clay minerals with a net negative charge arising from isomorphous substitution within the crystal lattice, caesium and strontium sorption is predominantly a cation exchange process. Strontium exchange with charge compensating sodium ions on clay minerals, in the absence of competing cations, results in high strontium R3 values until exchange with sodium is virtually completed. Strontium exchange for calcium ions markedly reduces the strontium R4 under similar conditions. This is consistent with calculations to determine the selectivity coefficient for the exchange reaction. For the exchange of divalent strontium for monovalent sodium ions, theory predicts that the selectivity of the clay to the divalent cation increases with its loading. This is not the case for the homo-, divalent exchange of strontium for calcium and the marginal difference in hydration energies of the two cations further depresses strontium-selectivity of clays. Clay minerals are selective to caesium ions because of their low hydration energy and the Rd for caesium exchange with sodium is higher than for potassium exchange with sodium under similar conditions. Caesium sorption can cause 2: 1 swelling clay minerals to physically alter their structure as caesium loading increases. For this reason, caesium exchange on smectites does not fit Langmuir nor Freundlich plots. Also, the selectivity coefficient was found to vary widely with loading, compared with potassium exchange on smectites or caesium exchange on non-swelling minerals. Complete caesium exchange on Los Trancos montmorillonite causes the interlayer to collapse. Desorption of caesium ions from planar surface and edge sites can be achieved but the majority of caesium in the interlayer region is resistant to desorption and strong acid attack.

Particle swarm optimization (PSO) is a well known population-based search algorithm, originally developed by Kennedy and Eberhart in 1995. The PSO has been utilized in a variety of application domains, providing a wealth of empirical evidence for its effectiveness as an optimizer. The PSO itself has undergone many alterations subsequent to its inception, some of which are fundamental to the PSO's core behavior, others have been more application specific. The fundamental alterations to the PSO have to a large extent been a result of theoretical analysis of the PSO's particle's long term trajectory. The most obvious example, is the need for velocity clamping in the original PSO. While there were empirical fndings that suggested that each particle's velocity was increasing at a rapid rate, it was only once a solid theoretical study was performed that the reason for the velocity explosion was understood. There has been a large amount of theoretical research done on the PSO, both for the deterministic model, and more recently for the stochastic model. This thesis presents an extension to the theoretical deterministic PSO model. Under the extended model, conditions for particle convergence to a point are derived. At present all theoretical PSO research is done under the stagnation assumption, in some form or another. The analysis done under the stagnation assumption is one where the personal best and neighborhood best are assumed to be non-changing. While analysis under the stagnation assumption is very informative, it could never provide a complete description of a PSO's behavior. Furthermore, the assumption implicitly removes the notion of a social network structure from the analysis. The model used in this thesis greatly weakens the stagnation assumption, by instead assuming that each particle's personal best and neighborhood best can occupy an arbitrarily large number of unique positions. Empirical results are presented to support the theoretical fndings. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Computer Science / Unrestricted