Thesis (M.A.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Michael Sexson. Includes bibliographical references (leaves 88-90).

Automotive active suspension, advanced seismic testing, and force/torque emulations of space manipulators are examples of applications, where the hydraulic actuator force control is required. In double-rod hydraulic actuators, the actuator force is the differential pressure across the actuator multiplied by the piston effective area. The focus of this work is to control the actuator force of a double-rod hydraulic actuator by controlling the differential pressure across the actuator. The double-rod hydraulic actuator of this study is run by two independent circuits: 1) electro-hydraulic actuation and 2) electro-hydrostatic actuation. In general, developing controllers for hydraulic actuators is challenging due to the presence of parametric uncertainties and uncertain nonlinearities. Also, a specific challenge in force control of hydraulic actuators is the limiting effect of environment dynamics on the maximum achievable tracking bandwidth. Considering the above challenges, in this research for the first time, quantitative feedback theory (QFT) is employed to control the hydraulic actuator force. Using QFT, a robust, linear, fixed-gain, and low-order controller is designed for each actuation system which: (i) keeps the closed-loop response within desired tracking bounds (ii) guarantees the closed-loop stability around desired operating points, (iii) rejects disturbance, and (iv) achieves desired tracking bandwidth. Among the performance criteria, special attention is paid to achieve high tracking bandwidth. Trade-offs between different performance criteria towards achieving high tracking bandwidth, are discussed. Experimental results are presented to validate that the performance criteria are satisfied by the designed QFT controllers. The QFT controllers are synthesized based on the families of frequency responses of the hydraulic actuation systems, which limits the stability results of the closed-loop system, only for these families of the frequency responses. In this thesis, to investigate the nonlinear stability of the closed-loop systems with QFT controllers, for the first time, Takagi-Sugeno (T-S) fuzzy modeling and its corresponding stability theory are used. The stability conditions are presented in the form of linear matrix inequalities (LMIs). As a result, the nonlinear stability of the designed QFT controllers for both the actuation systems is proven in the presence of parametric uncertainties. / February 2016

Vehicle yaw stabilization and rollover prevention are two key factors in safety of vehicles. Designing a controller that can address both of the above safety concerns is of interest. In addition, it is essential that the performance of such a controller is evaluated properly. This can be done using a proper stability analysis. The above research problem is challenging for two reasons. First, maintaining both of the objectives, yaw stabilization and rollover mitigation, is contradictory at some instances, specifically when the vehicle is close to the verge of wheel lift-off. Second, the complexity of the dynamics of vehicle systems, which mostly arises from tire dynamics, makes the problems of controller design and stability analysis more challenging. In this Ph.D. thesis, a novel method for stability analysis of dynamical systems using the concept of Lyapunov exponents is proposed. The proposed method for stability analysis does not have the limitations of the current methods, and more specifically, can identify boundaries of the whole stability regions of attractors in a dynamical system. Furthermore, this method is computationally efficient and can be applied to general forms of nonlinear systems. The proposed stability analysis scheme is applied to the closed loop systems of ground vehicles with T-S fuzzy controllers for the purpose of evaluating and comparing the performance of the systems. The T-S fuzzy controllers integrate yaw stabilization and rollover avoidance. The ground vehicles that are studied in this research consist of torsionally flexible and torsionally rigid vehicles, which have differences in their dynamics because of the torsional compliance in their frames. The torsional compliance plays an important role in the dynamics, specifically for long vehicles, leading to different rollover indexes in the front and rear axles of the vehicles. The T-S fuzzy controllers are capable of prioritizing the contradictory objectives, and capturing all the essential complexities of dynamics of the systems. / February 2016

One of the most unique and striking features of T. S. Eliot's poetry up to and including The Waste Land is its imagery. Far from being mere decoration, the images in these poems play a vital role in the process of poetic communication. This paper attempts to examine in some detail Eliot's image, the important influences which contributed to its development, and its function in these poems. The poems of Prufrock and Other Observations show that Eliot had perfected his own "imagism" before coming into contact with Imagist theories through Ezra Pound in 1914, These poems reveal Eliot's characteristic method of using images—which are mainly precise renderings of an urban scene—as "objective correlatives" for a wide range of thoughts and feelings, in order to dramatize the plight of the poem's speaker. It was through a close study of such figures as Charles Baudelaire, Jules Laforgue, the Jacobean dramatists, the Metaphysical poets and the philosopher Henri Bergson, that Eliot discovered his own poetic voice. Although he knew little before 1914 of the Imagists— notably T. E. Hulme, who was to influence him much later— Eliot's "imagism" shows certain similarities, in theory and practice, with the work of this important poet and theoretician. These similarities are examined in this paper to help define Eliot's own "imagism". After 1914, Ezra Pound played an important part in the development of Eliot's imagery. In general, Pound showed Eliot methods for extending to the limit the impersonality which was already a feature of Eliot's poetry. This led, through a mutual interest in the poems of Théophile Gautier, to Eliot's satirical poems in the Poems 1920 volume. These poems juxtapose concepts in the form of concrete images, many of which are drawn from a wide variety of literary sources. But Eliot was restricted by Gautier's rhyming quatrain: in the satires, dramatic intensity is sacrificed for excessive superficiality and undue complexity. "Gerontion," however, marks a return to the energy of the Prufrock poems by using images to present an awareness of individual and cultural neurosis. Finally, The Waste Land marks a climax in Eliot's development by fusing and harmonizing methods previously acquired, and achieves unity through a complex pattern of images, many of which grow out of the preceding poems. At their best, these images are not only precise sensual experiences but powerful expressions of feelings and thoughts. As such, they give ample proof that the image in Eliot's poetry is the primary means of poetic expression. / Arts, Faculty of / English, Department of / Graduate

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The thesis consists of a selection of original poems and an essay on the literary relationship between Matthew Arnold and T. S. Eliot. The poems are loosely related in theme; they are the responses of the poet to the various forces in his upbringing, such as literature, religion and the American Southwest. The essay compares the literary criticism of Arnold and Eliot, the foremost critics of their respective periods, with special attention to Eliot's criticism of Arnold. The conclusion is that despite this criticism Eliot accepted Arnold's major critical precepts and perpetuated in his own work Arnold's central concerns about literature and culture.

Made available in DSpace on 2016-03-15T19:46:52Z (GMT). No. of bitstreams: 1 Tania Silva.pdf: 938904 bytes, checksum: efb439849ca426d433027ef04bdbc492 (MD5) Previous issue date: 2006-02-24 / This work aims at analysing the Anglo-American poet and essayist Thomas Stearns Eliot s use of intertextuality in his poem The Waste Land, published in 1922.Our analysis focuses on myth and its function within the poem. We have chosen four myths, three of them Pagan (Sibila, Tiresias and The Fisher King) and one Christian (The Holy Grail). The latter has a deep relationship to The Fisher King myth. We will mention theoretical concepts referring to intertextuality and myth and will present a survey of the poem as a whole. We will also report form briefly on the political-social situation of Europe at the time in which the poem was written, and the poet s main achievements in his career. Our next focus will be the analysis of the above mentioned myths as well as their function and relevance within the context of the poem. / O presente trabalho tem por objetivo analisar a intertextualidade no poema The Waste Land, do poeta e ensaísta anglo-americano Thomas Stearns Eliot, publicado em 1922. Focaliza o mito e sua função dentro do poema. Foram escolhidos particularmente quatro mitos, três pagãos (Sibila, Tirésias e Rei Pescador) e um cristão (Santo Graal), sendo que este último tem uma relação estreita com o mito do Rei Pescador. Examinar-se-ão postulados teóricos sobre o mito, a intertextualidade e a situação político-social da Europa, na época em que Eliot compôs o poema, bem como da trajetória do poeta.

Ce travail de thèse traite de l’analyse de la stabilité et la stabilisation des systèmes non-linéaires représentés par des modèles T-S. L’objectif est de réduire le conservatisme des conditions de stabilité, obtenue par la méthode directe de Lyapunov, et écrites, dans la mesure du possible, sous forme de LMIs. Dans ce cadre, deux contributions principales ont été apportées. Tout d’abord, nous avons proposé de nouvelles conditions de synthèse non-quadratique de lois de commande, strictement LMIs et sans restriction d’ordre, pour les modèles T-S via des FLICs. En effet, dans ce contexte, les résultats de la littérature ne sont valables que pour les modèles T-S d’ordre inférieur ou égal à 2. Afin de lever cette restriction, les conditions ont été obtenues grâce à la démonstration d’une propriété de dualité. Ensuite, peu de travaux traitant de la spécification des performances en boucle fermée, de nouvelles conditions LMIs (quadratiques et non-quadratiques) ont été proposées via le concept de D-stabilité. Dans un premier temps, la synthèse de lois de commande PDC et non-PDC D-stabilisantes a été proposée pour les modèles T-S nominaux. Ensuite, ces résultats ont été étendus au cas des modèles T-S incertains. De plus, nous avons mis en évidence, au travers d’un exemple de D-stabilisation en attitude d’un modèle de drone quadrirotor, que les modèles T-S incertains pouvaient être avantageusement considérés lorsque les non-linéarités d’un modèle non-linéaire dépendent à la fois de l’état et de l’entrée. / This work deals with the stability analysis and the stabilisation of nonlinear systems represented by T-S models.The goal is to reduce the conservatism of the stability conditions, obtained through the direct Lyapunov methodand written, when it is possible, as LMIs. In this framework, two main contributions has been proposed. First ofall, we have proposed some new conditions based on FLICs, strictly LMIs and without any order restrictions, forthe non-quadratic design of control laws devoted to stabilize T-S models. Indeed, in this non-quadratic context,the existing works are only available for 2nd order T-S models. In order to unlock this restriction, the proposed conditions have been obtained based on the proof of a dual property. Then, starting from the fact that few worksdeals with the closed-loop performances specification, some new LMI conditions (quadratic and non-quadratic)have been proposed via the D-stability concept. As a first step, D-stabilizing PDC and non-PDC controller designhas been considered for nominal T-S models. Then, these results have been extended to uncertain T-S models.Moreover, it has been highlighted, from an example of the attitude D-stabilization of a quadrotor model, that wecan make use of uncertain T-S models to cope with nonlinear models involving nonlinearities depending on bothstate and input variables.

T.S. Eliot's statement that myth is an ordering device in literature 'is constantly belied by his use of myth in his own poems'. This is the belief of the American critic Richard Chase, noted for his work on myths and mythological themes in English and American literature. Whether or not Chase is right must emerge from the chapters which follow. The purpose will be to examine the effects of the use of myths and mythological patterns on Eliot's work in general, rather than to annotate individual mythological allusions. Simply to recognise an allusion is to raise a question, not to answer one: for we have then to decide what the writer hope to achieve by its use, and whether or not he has succeeded. Unless they lead on to such questions, lists of sources contribute little to our understanding of a work. Far more important than incidental allusions are the mythological themes and patterns on the larger scale, which reveal themselves in recurrent allusions and in basic patterns of symbolism. Again, merely to recognise such a pattern is inadequate: in every case a discovery of its function in both the poem's (or play's) structure and the poet's technique should be our main concern. ... Eliot himself has made it clear that in his case the use of myths and mythological patterns has often been a fully conscious, even self-conscious process. Therefore we may apply to his work the questions mention by Norman: what functions the myths fulfil within individual works; and why Eliot uses them in the first place. This last question leads us back to a more fundamental one; why do many writers, especially modern ones, use myths 'in the first place'? The problem involves discussion of the relation between myths and literature and of the nature of myths themselves, this forms the material of the first chapter. The other chapters will deal with some of Eliot's works, attempting to explain and analyse his use of myths in them, and to illustrate its importance in each case.