During the past 60 years fluid-structure interaction in a wide range of three dimensional circular cylinder problems have been studied. Initial problems considered a rigid wall structure which were solved using impedance model comparisons. Soon after, further solution techniques were used, such as computer simulation, transfer matrix methods and finite element techniques. However such problems were only valid for low frequencies when compared with experiments, this was because that did not include higher order modes. The importance of higher order modes was then established and studies have since included these modes. More recently, mode matching methods have been used to find the amplitudes of waves in structures comprising two or more ducts. This has been done with using an orthogonality relation to find integrals which occur from the application this method. This methodology is demonstrated in as background information and is applied to prototype problems formed of rigid ducts. The rigid duct theory led to the consideration of elastic shells, of which several shell modelling equations were available from the vibration theory. In this thesis, the Donnell-Mustari equations of motion are used to model thin, elastic, fluid-loaded shells of circular cross-section. It is demonstrated that generalised orthogonality relations exist for such shells. Two such relations are found: one for shells subject to axisymmetric motion and one for shells subject to non-axisymmetric motion. These generalised orthogonality relations are new to the field of acoustics and are specific to shells modelled with the Donnell-Mustari equations of motion. The mode matching method is used to find the amplitudes of waves propagating in prototype problems and the generalised orthogonality relations are used to find integrals which occur through this method. Expressions for energy for all considered structure types are used to find the resulting energy for each prototype problem and results for equivalent problems are compared. In addition, verification of the resulting amplitudes is done by ensuring that the matching conditions are suitably satisfied. It is anticipated that the method will have application to the understanding and control of the vibration of cylindrical casings such as those enclosing turbo-machinery. Another application of the method would be the tuning of cylindrical casings, such as those featured on car exhaust systems or HVAC (heating, ventilation and air conditioning) systems.

[pt] A presente análise debate, comparativamente, as teorias da democracia e da cidadania nas obras de Guillermo O Donnell e Étienne Balibar a partir dos seus respectivos títulos, quais sejam, Democracia, Agência e Estado: teoria com intenção comparativa (O DONNELL, G. 2010) e Ciudadanía (BALIBAR, É.2012). São dissecadas ambas as teorias, a primeira de origem liberal e a segunda marxista, com base nas abordagens comuns ou particulares de cada um dos autores, discutindo-se as noções e interações de interpretações incompatíveis sobre elementos como estado, democracia, cidadania, individualidade, exclusão, globalização, burocracia, representação, conflito, entre outros. Não obstante, por conta da vasta bagagem teórica dos autores, bem como o estreito diálogo que as suas teorias mantém com as obras tomadas como referência pelos autores, o trabalho se desenvolve também no aprofundamento destas leituras estruturantes das respectivas teorias. Este estudo é revelador das discrepâncias e aproximações de tais perspectivas tão celebremente divergentes, sem contudo, deixar de assumir preferência pela corrente crítica radical balibariana – cabendo ressalvas -, fazendo sobressair o seu caráter crítico contra-hegemônico à via liberal de O Donnell. Ainda, o estudo permite, com base na atualidade das teorias analisadas, uma percepção crítica da inquietante esfera política atual, em vista dos recentes movimentos populares que espontaneamente tomaram parte do globo a partir de 2010, desde movimentos imediatamente insurrecionais até massivos protestos pejorativamente denominados sem causa. / [en] This analysis debates and compare the theories of democracy and citizenship in the works of Guillermo O Donnell and Étienne Balibar from their respective books, namely, democracia, agência e estado: teoria com intenção comparativa (O donnell , g. 2010) and ciudadanía (Balibar, É. 2012). I examine both theories, one liberal and the other radically democratic, based on the common or divergent approaches of each author. some concepts and perspectives are particularly relevant, such as state, individuality, exclusion, globalization, bureaucracy, representation, conflict, among others. nevertheless, due to the vast theoretical background of the authors and the close dialogue that their theories keeps with the works taken as reference by the authors, this work develops deeply these structural readings of the respective theories. It s objective reveals the discrepancies and common ideas of such traditional divergent perspectives,however, in preference for the Balibarian radical critique, bringing out it s counter-hegemonic aspects against the liberal route of O Donnell. moreover, the study allows, based on the topicality of the analyzed theories, a critical view of the disturbing current political context, in face of the recent popular movements that spontaneously emerged all over the globe from 2010, since immediately insurrectionary movements to mass protests called pejoratively without cause.

The lowest natural frequencies of thin-walled noncircular fiber-reinforced composite cylinders, specifically cylinders with elliptical cross sections, are investigated. Of interest is the variation of the lowest natural frequency, the so-called fundamental frequency, as a function of wall laminate properties, cross-sectional eccentricity and other cylinder geometric parameters. Both simple and clamped support boundary conditions are investigated. Laminate properties that are uniform with circumferential location and laminate properties that vary with circumferential location, by way of varying laminate fiber angle with circumferential location, are considered. As the radius of curvature of a noncircular cylinder varies with circumferential location, it is logical to consider the influence of circumferentially varying fiber orientation on the fundamental frequency. The analysis for predicting the fundamental frequency is based on Donnell shell theory, linear elastic properties, and the use of Hamilton's Principle in conjunction with the Rayleigh-Ritz technique. By use of a so-called shape factor, the magnitude of cylinder normal displacements are modulated to be larger in the regions of the cross section with the largest radius of curvatures and smaller in the regions with the smallest radius of curvature. The final equations for predicting the fundamental frequency are quite complex, but a series of approximations results in a hierarchy of simpler equations, the simplest being referred to as Lo's approximation. The prediction of the fundamental frequencies is spot checked by comparing the results as predicted by the various levels of approximation with predictions of a shell-based finite element model. Considering uniform laminate properties, comparisons between the developed analysis and the finite element model are good for all levels of simpler equations, and excellent in some cases. The developed analysis is subsequently used for parameter studies. It is found that compared to a circular cylinder of the same circumference and with uniform laminate properties, the fundamental frequency of an elliptical cylinder is always less. Surprisingly, based on the results obtained, it appears that for a given cylinder geometry the fundamental frequency is not particularly sensitive to wall lamination sequence, though the wave number in the circumferential direction of the mode shape associated with the fundamental frequency is sensitive to lamination sequence. Considering cylinders with circumferentially varying fiber orientation, comparisons between the developed analysis and the finite element model for most of the cases studied are good. However, the developed equations are limited since it is difficult to find a set of known functions to describe the deformation of an arbitrary lamination sequence when applying the Rayleigh-Ritz technique. In general, in can be concluded that the effect of varying fiber orientation on the fundamental frequency is much less than the influence of cylinder aspect ratio. It can also be concluded that the developed analysis would be an excellent tool for design purposes, as the calculation of the fundamental frequency is done quickly, and design trade-offs studies would be easy. / Ph. D.