Dissertations / Theses on the topic 'Babbits'

Written in 1999, Concerto Piccolino is a part of the Composer's Guild of New Jersey Vibraphone Commission, which contains a collection of twelve soli written exclusively for vibraphone. Concerto Piccolino presents vibrant opportunities for both performer and listener to experience the compositional world of Milton Babbitt. With its limited register, ability to control duration and create extreme dynamics, the vibraphone serves as an appropriate vehicle for Babbitt's multi-dimensional style. The intent of this study is to first situate this work into Babbitt's compositional output as well as referencing Babbitt's other works for solo percussion. Next, an investigation into the background structure will provide a recommended analytical framework. Included is a performance guide for how these structures should be realized via surface materials throughout the interpretive and internalization stages of the work. Examining a recommended progression from analysis through performance will demonstrate Concerto Piccolino's significance and proper place in the standard repertoire of percussion. The study concludes with discussing connections to pedagogy and how the importance of Babbitt's work, as well as other composers of serious music, is vital to the forward progress of music performance.

Cette thèse explore les rapports entre la formalisation mathématique, ses implications dans les pratiques compositionnelles et ses répercussions sur l’interprétation analytique. Elle se base sur l’étude de Semi-Simple Variations pour piano (1956) de Milton Babbitt, de Nomos Alpha pour violoncelle (1965-1966) de Iannis Xenakis (1921/22-2001), et d’une sélection de textes théoriques publiés par les compositeurs autour de ces deux œuvres.L’argumentaire est divisé en trois parties. La première étudie les textes théoriques afin d’en dégager les éléments formalisés (ou résultant de la formalisation) ainsi que les indices permettant d’en retracer les implications dans les pratiques compositionnelles. Ces éléments sont précisés dans la deuxième partie via la reconstitution des traces laissées par les composantes formalisées dans les textes musicaux (« modèles théoriques »). Ce travail est mené sur les deux œuvres proposées à l’analyse puis élargi à d’autres œuvres. Les modèles théoriques de deux d’entre elles étaient jusque-là restés inédits : Three Compositions for Piano de Babbitt (1947-1948) ; et Akrata de Xenakis pour 16 vents (1964-1965). La troisième partie soumet Semi-Simple Variations et Nomos Alpha à deux analyses : la première étudie les modèles théoriques, directement liés aux univers formels, alors que la seconde examine les surfaces sonores et comment elles articulent et/ou contredisent les éléments dégagés au niveau des modèles. Tout en soulignant le rôle fondamental, quoique très différent, joué par la formalisation dans les univers compositionnels de Babbitt et de Xenakis, la distance séparant les modèles théoriques des surfaces sonores amènent à considérer l’apport des premiers dans l’interprétation analytique comme étant de nature avant tout heuristique. En tant que traces de la pensée du compositeur, les modèles théoriques peuvent néanmoins suggérer de nouvelles pistes et méritent d’être intégrés à des recherches futures
This thesis explores the links between mathematical formalization, its implications in compositional practices, and its repercussions on the analytical interpretation. It is based on the study of Milton Babbitt’s Semi-Simple Variations for piano (1956), on Iannis Xenakis’ Nomos Alpha for violoncello (1965-1966), and on a selection of theoretical texts published by the composers around these two works. The argumentation is divided in three parts. The first studies the theoretical texts with the aim of extracting from them the components that are formalized (or result form formalization) as well as the indices pointing towards their implications in the compositional practices. These are then put into sharper view in the second part, through the reconstruction of the traces left by these components in the musical texts (“theoretical models”). This reconstruction is first conducted on the two main works considered before other works are considered. The theoretical models of two of them had until now remained unknown: Three Compositions for Piano by Babbitt (1947-1948) ; and Akrata for 16 winds (1964-1965) by Xenakis. The third part submits Semi-Simple Variations and Nomos Alpha to two analyses: one is aimed at the theoretical models, directly linked to the formal universes, the second examines the musical surfaces and at the way they articulate and/or contradict the elements observed in the models. While underlining the fundamental - though very different - role played by mathematical formalization in Babbitt’s and Xenakis’ compositional universes, the distance that separates the theoretical models from the musical surfaces brings one to consider the role of the former within the analytical enterprise as essentially heuristic. As traces of the composer’s thinking, the theoretical models may however suggest new approaches and deserve to be fully integrated in future research

Thesis (M.A.)--University of Nevada, Reno, 2007.
"December, 2007." Includes bibliographical references (leaves 125-128). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2008]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

This thesis implements Milton Babbitt's time-point system for music composition via the creation of a computer software application for the Macintosh computer. This system asks the composer to enter musical information, which is used to calculate pitch, duration, articulation, texture, octave, and silence, for the time-point composition. The application generates a file of musical information that is compatible with a performance application; the performance application will execute the composition communicating with MIDI-compatible musical instruments.The purpose of this project was to create a compositional tool that would implement the time-point system by reducing hours of hand calculation and tedium, and would provide an accessible and efficient approach to time-point composition. It is intended that this application be used to assist both the serious composer as well as the student of music composition.
School of Music

Thesis (D.M.A.)--University of North Texas, 2004.
System requirements: Adobe Acrobat Reader. Accompanied by 4 recitals, recorded Mar. 25, 2002, Mar. 10, 2003, Oct. 6, 2003, and Oct. 18, 2004. Includes bibliographical references (p. 54-55).

This dissertation discusses the potential of the snare drum as a solo concert instrument. Four pieces from a collection entitled The Noble Snare are used for demonstration ("Homily" by Milton Babbitt, "Composed Improvisation for Snare Drum" by John Cage, "Peeping Tom" by Dan Senn, and "The Noble Snare" by Stuart Saunders Smith). In the absence of many traditional musical devices (i.e. melody and harmony), alternative means of expression are used by the composer. Each piece is discussed with regard to its distinctive compositional approach and inherent performance issues. Information is also given pertaining to the background of the Noble Snare series. This includes: the inspiration for the project, editorial issues, and its influence on snare drum performance. Much of this research was completed through interviews by with author with Sylvia Smith, publisher of The Noble Snare and owner of Smith Publications.

In general, the bearing alloys have two types of microstructure i.e., either a soft matrix with discrete hard particles or a continuous matrix of the harder metal with small amount of the softer metal finely dispersed in it. The aluminium and copper based bearing alloys which are widely studied fall in the second category. However, the bearing materials which have been studied have micron sized dispersoids. In recent times, it is possible to produce nanoscale dispersoids in a hard matrix by the novel processing route of rapid solidification. This offers an opportunity to study the small length scale effect on tribological processes. In this thesis, we deal with aluminium alloys where nanoscaled dispersions of lead, bismuth and indium are produced by rapid solidification processing. Chapter 1 of the thesis is an introduction, followed by Chapter 2, which reviews the literature on nanomaterials. Special attention is given to the monotectic system, followed by a brief description on friction and wear of materials which is necessary for our present investigation. The details of experimental and characterisation techniques are given in Chapter 3. In Chapter 4, we present a brief study of white metal bearings (babbit). Tin-based babbit of composition, Sn-6wt% Cu-llwt% Sb was studied. The study of babbit was mainly carried out with the idea that it could serve as a benchmark for subsequent studies in aluminium alloys, in terms of tribological properties. In particular, we have carried out a detailed electron microscopic investigation on the phases present in the bearing alloy. The friction and wear behaviour of this material confirms the proper calibration of our setup for wear studies. This is followed by a detailed study on the synthesis, microstructure and tribological behaviour of nanodispersed aluminium alloys, Al-6wt% Pb and Al-10wt% Pb in Chapter 5. For comparison, we have also studied melt-spun aluminium without dispersoids. Detailed electron microscopic characterisation indicates that lead has a cube on cube orientation relationship with the aluminium matrix, and the particles exhibit a lognormal distribution with the mode of the particle size distribution being 15 nm. The pin on disc results suggest a distinct lowering of coefficient of friction corresponding to pure aluminium (μ= 0.40) and as cast aluminium-lead alloys (μ= 0.41). Detailed SEM studies indicate a tribolayer consisting primarily of Al, Pb and Fe. The later comes from the counterface material. Our results clearly indicate that at an early stage, little or no oxidation takes place at the sliding interface. TEM observations indicate significant deformation of lead particles in the sub-surface region. The observations suggest spreading of the lead, which acts as a lubricating layer. Wear behaviour is primarily adhesive and follows Archard's wear law. However, the rate of wear is less than that reported by other investigators on micronsized lead dispersions in aluminium. In Chapter 6, we present the results for alloys dispersed with nanosized indium and bismuth. We show that indium particles on melt-spinning exhibit both cubic and tetragonal crystal structure. The indium particles are coarser (with a mode of 25 nm) than the lead and bismuth particles (which have mode of 15nm). The bismuth containing alloys have a lower wear rate and coefficient of friction compared to lead and indium alloys. However, both indium and bismuth particles do not follow Archard's wear law and the wear vs load graph shows a non-linear behaviour. The results are discussed in terms of known mechanisms of the coefficient of friction and wear. Chapter 7 gives the salient conclusions while in Chapter 8 we discuss some of the unanswered questions and the potential for future work in this field.

Дисертаційна робота присвячена розробленню принципів зносостійкості, що ґрунтуються на закономірностях зв’язку структуроутворення з геометрією трибологічного контакту. Зазначені принципи реалізовано при цілеспрямованому регулюванні фазового складу конструкційних та інструментальних сталей, що пов’язує елементи мікроструктури зі схемою контактної взаємодії поверхонь твердих тіл при терті та забезпечує високий опір зношуванню та мінімізацію пошкоджуваності поверхонь контакту. Виявлено, що морфологія карбідної фази сталей 40Х та 40ХНМ є одним з основних факторів, який впливає на рівноважну шорсткість, структурно-геометричні параметри та несучу спроможність поверхні контакту, які формуються при терті та позначаються на їхніх трибологічних характеристиках. Показано, що отримання в структурі сталей Х6ВФ, 9ХФ і 7ХНМФБ на місці крупних тугоплавких легованих карбідів дисперсного мартенситу із залишками цих карбідів сприяє суттєвому підвищенню зносостійкості зазначених сталей завдяки зникненню міжфазних меж «карбід-матриця». За результатами нейромережевого моделювання сертифікованих структурно-геометричних параметрів поверхні залежно від її шорсткості проведено аналіз несучої спроможності поверхні контакту сталі 40Х під час тертя.
Диссертационная работа посвящена разработке принципов износостойкости, основанных на закономерностях связи структурообразования с геометрией трибологического контакта и их реализация в управлении работоспособностью низколегированных конструкционных и инструментальных сталей при обосновании оптимальных режимов термической обработки. Предложены основные закономерности и требования к организации структуры, а также пути целенаправленного регулирования фазового состава конструкционных и инструментальных сталей, связывающих элементы микроструктуры со схемой контактного взаимодействия поверхностей твердых тел при трении, обеспечивающих высокое сопротивление износу и минимизацию повреждаемости поверхности контактного взаимодействия. На основании сравнительного анализа размерных параметров и характера распределения интерметаллидов SnSb в структуре баббитов Б83 и БТ относительно размеров и распределения пятен контакта при взаимодействии твердых тел при трении сформулированы основные закономерности и требования к организации износостойких антифрикционных структур. Установлено, что растущая неравномерность распределения углерода в сталях 40Х и 40ХНМ с повышением температуры закалки до 1050 С способствует увеличению размеров и количества высокоуглеродистых кристаллов игольчатого мартенсита и выделению в середине них на микродвойниковых границах при высоком отпуске более крупных в сравнении с пакетным мартенситом карбидов, стабильных к распаду при пластической деформации, образуя микрообъемы материала, обладающие более высокими относительно окружающей микроструктуры механическими характеристиками и устойчивостью к разрушению при фрикционном контакте. Показано, что создание гетерогенной по прочностным характеристикам структуры в указанных сталях, близкой к схеме контактного взаимодействия, является одним из решающих факторов уменьшения интенсивности износа как образцов, так и контртела. Дальнейшее увеличение температуры закалки до 1160 С хотя и приводит к образованию еще большей неравномерности распределения углерода с еще большими кристаллами игольчатого мартенсита, но при этом значительно увеличивается расстояние между микрообъёмами материала с повышенными механическими характеристиками и уменьшается их количество на поверхности трения, уменьшая стойкость к износу по сравнению с образцами, закаленными от 1050 С. Выявлено, что морфология карбидной фазы является одним из основных факторов, влияющих на равновесную шероховатость, структурно-геометрические параметры и несущую способность поверхности контакта, формирующиеся при трении и сказывающиеся на их трибологических характеристиках. На примере стали 08Г2С, направленной на гребень вагонного колеса, установлено, что формирование в литом материале гетерогенной по строению и механическим характеристикам структуры приводит к существенному уменьшению ее износа по сравнению с гомогенной. Увеличение дисперсности структуры первичных кристаллитов при их перпендикулярной ориентации к поверхности трения приближает структуру к схеме контактного взаимодействия и способствует повышению износостойкости металла в литом состоянии. Изучено влияние температурно-временных условий закалки инструментальных сталей Х6ВФ, 9ХФ и 7ХНМФБ, содержащих в своей структуре крупные тугоплавкие карбиды, которые могут выполнять роль пятен контакта. Показано, что замена потенциальных пятен контакта в виде тугоплавких легированных карбидов после стандартной термической обработки на опорные микроучастки со структурой дисперсного мартенсита с остатками этих карбидов способствует существенному повышению износостойкости указанных сталей благодаря исчезновению межфазных границ «карбид-матрица», уменьшению вероятности выкрашивания крупных карбидов и увеличению стойкости к разрушению при контактном взаимодействии микрообъёмов с повышенными механическими характеристиками. Осуществлена адаптация выбранной архитектуры искусственной нейронной сети – функционала множества табличных функций. Спрогнозировано изменение физико-механических свойств поверхности контакта стали 40Х и связанную с ней динамику изменения сопротивления износу в зависимости от температуры закалки. По результатам моделирования сертифицированных структурно-геометрических параметров поверхности в зависимости от ее шероховатости проведен анализ несущей способности поверхности контакта образцов стали 40Х при трении.
The thesis is devoted to the development of wear resistance principles, which based on connection regularities of structure formation with tribological contact geometry. These principles by targeted regulation of phase composition of constructural and tool steels by connection of microstructure elements with the contact interaction scheme of solid surfaces during friction was realized and provides high wear resistance and minimizes damages of contact surfaces. It was revealed that the carbide phase morphology of 40X and 40XHM is one of the main factors affecting the equilibrium roughness, structural-geometric parameters, and the bearing capacity of the contact surface formed upon friction and affect their tribological characteristics. It is shown that obtaining in the structure of X6ВФ, 9XФ and 7ХНМФБ tool steels in the place of large refractory alloyed carbides of disperse martensite with the residues of these carbides contributes to a significant increase in the wear resistance of these steels due to the disappearance of the carbide matrix interfacial boundaries. According to the results of neural network modeling of certified structural-geometric parameters of the surface, depending on its roughness, the bearing capacity of the 40X steel contact surface during friction was analyzed.

L'application de méthodes algébriques en musique représente une démarche récente dans la recherche musicale. Une réflexion historique sur l'émergence du concept de structure algébrique en musique met en évidence la place centrale occupée par trois compositeurs/théoriciens du XXe siècle : Milton Babbitt, Iannis Xenakis et Anatol Vieru. A partir de leurs propositions théoriques, cette étude développe une réflexion approfondie sur la notion de théorie musicale dans ses applications aussi bien analytiques que compositionnelles. Elle offre également une formalisation algébrique de la Set Theory et de ses développements transformationnels tout en discutant les rapports entre la tradition analytique américaine et la démarche théorique formelle en Europe. Les concepts abordés permettent de définir la place d'une démarche computationnelle en musicologie et ouvrent des questions philosophiques sur le rapport entre mathématiques et musique
The application of algebraic mtehods to music is a relatively new approach in musical research. We analyse the problem of the emergence of algebraic structures in music by looking at three main figures of twentieth-century theorists/composers : Milton Babbit, Iannis Xenakis and Anatol Vieru. Some of their music-theoretic contructions are the starting point for a discussion on the notion of music theory in some analytical as well ax compositional applications. This work discusses an algebraic formalisation of Set Theory and its transformational developments from a perspective which includes an analysis of the relationships between American tradition and a formalised European approach. The concepts elaborated in this work lead to a definition of the place of a computational approach in musicology and open several philosophical questions on the relationships between mathematics and music

This thesis explores how partitions and partition lattices can provide insight into small-scale and large-scale analytical relationships in several twelve-tone compositions by Milton Babbitt. Chapter 1 outlines the concept of partition lattices, as they have recently been described by Richard Kurth; summarizes the definitions and conventions of the lattice model; and suggests how they might be applied to Babbitt's music. Chapter 2 examines how recurring hexachords and hexachordal partitions arise from lattice interactions of the trichordal array partitions in the Woodwind Quartet (1953). Chapter 3 applies the lattice model to the first twelve measures of the Composition for Viola and Piano (1950) and explores how partitions corresponding to the surface texture are all subpartitions of a single hexachordal partition. Chapter 4 examines how partition lattices suggest various different levels of partition structure in the String Quartet No. 2 (1954). Chapter 5 summarizes the conclusions of the preceding chapters, outlines the limitations of the analytical method, and discusses the possibilities for applying partition lattices to the all-partition array works of Milton Babbitt.

碩士
東吳大學
音樂學系
94
As Serialism arises after World War II in the twentieth century, serial techniques made a transition from twelve-tone music to integral serialism. A series was no longer restricted to the domain of pitch, but expanded to include duration, dynamics, tempo, register, and timbre. The contemporary composer Milton Babbitt (1916 –) is regarded as the pioneer of integral serialism in America. Through the analysis of Milton Babbitt’s piece “All Set, for Jazz Ensemble, 1957”, this thesis will explore the musical thinking and creative techniques of a composer’s piece, and serve as an initial step towards the fundamentals of a developing music theory. The Pitch-class Set analytic method will be used in this thesis. The technique is first employed by looking at the basics of pitch, then delving into what is hidden in the piece, apart from pitch, in the arrangement of musical elements. In addition to Babbitt’s mathematical background, the integration of mathematical concept and musical theory is evident in his pieces. His focus on logic and discipline has increased the sensibility of musical layers. For instance, he implemented aggregate and dimension from a mathematical point of view into his musical creativity, to liberate the musical thought which is otherwise full of the scientific spirit. Although Babbitt’s serial techniques originated from the early twelve-tone system, he has revolutionized the traditional barrier, allowing the use of musical elements to be optimized. In “All Set”, Babbitt has immersed the elements of Jazz music, including its specific style of instrumentation into the idea of musical composition. The composer has combined extreme and contrasting ends of musical types, one being serial music which represents seriousness and control of musical arrangement, the second being Jazz music, representing the flexibility and openness. This research is therefore intended to search out and convey the remarkable relationship of these two different styles. ------------------------------------------------------------------------------------------------------- Recital Program 1. Fanfare for three trumpets 2. Quintet for clarinet, two violins, viola and violoncello 3. Three Piano Pieces 4. Two Rivulets for soprano, alto flute, violoncello and piano 5. Three Movements for chamber orchestra 6. Brass Sextet for two trumpets, two horns, trombone, and tuba

碩士
國立中山大學
外國語文學系
84
This thesis is a sociological study of the contradictions inherent in capitalism and the American dream of success. It deals primarily with The Great Gatsby, Poor White, and Babbitt, three important American novels of the twenties. The reason why I choose them is that they exhibit a marvelous concurrence of dreams, fears, hopes, and frustrations caused by the compelling cultural myth. The first chapter introduces the contemporary social and cultural backgrounds that have inspired the writers of this time. It emphasizes the contradictory strands intrinsic both in the success myth and capitalist system. The second chapter shows the way Fitzgerald portrays the beautiful and the ugly aspects of the success dream. It points out his ambivalent attitude toward money and particularly the American dream. The third chapter examines how the technological progress engenders the chasm between the country and the city. America, as Anderson shows, is transformed into a land awash with the machines. The fourth chapter demonstrates how the life of a successful man is reduced to pettiness and insignificance. The pursuit of success, as Lewis displays, is poignantly rediculed and satirized. The fifth chapter is a theoretical review of the cultural contradictions. It shows that the doubled-edged success myth, in fact, echoes the central characteristics of capitalism: rationality and irrationality. It is probably this tension-filled myth that leads the three novelists to respond ambiguously to the material success.

Chiu Chau-ming.
Thesis (M.Mus.)--Chinese University of Hong Kong, 2003.
Includes bibliographical references (leaves 113-124).
Abstracts in English and Chinese.
Content --- p.i
Chapter A --- Abstract --- p.iii
Chapter B --- List of Examples --- p.v
Chapter C --- List of Tables --- p.vii
Chapter D --- Typographic Conventions --- p.ix
Chapter Chapter 1 --- Introduction --- p.1
Chapter Chapter 2 --- Theoretical Concepts --- p.4
Chapter 2.1. --- All-combinatorial hexachords --- p.4
Chapter 2.2. --- Array and lyne --- p.6
Chapter 2.3. --- "All-partition array, super-array" --- p.9
Chapter 2.4. --- M Operation / Transformation --- p.11
Chapter 2.5. --- Time-point --- p.12
Chapter Chapter 3 --- Structural Anatomy --- p.15
Chapter 3.1. --- Properties of the Twelve-tone Row --- p.19
Chapter 3.2. --- Properties of the Array --- p.25
Chapter 3.3. --- Array Transformations --- p.30
Chapter 3.4. --- Projection of Array in Pitch and Temporal Domains --- p.33
Chapter 3.5. --- Super-arrays --- p.37
Chapter Chapter 4 --- Surface Details --- p.41
Chapter 4.1. --- Statements of complete row-form --- p.42
Chapter 4.2. --- Array element repetition and aggregate size --- p.47
Chapter 4.3. --- Locations of D-Hexachords --- p.57
Chapter 4.3.1. --- Two-guitar duet --- p.59
Chapter 4.3.2. --- Flute-guitar duet --- p.64
Chapter 4.3.3. --- Violin-viola duet --- p.69
Chapter 4.4. --- Realization of even-partitioned aggregates 62 and 26 --- p.74
Chapter 4.5. --- Time-point realization --- p.81
Chapter Chapter 5 --- Summary and Conclusion --- p.88
Chapter Appendix 1 --- Partition Types of 58 Aggregates --- p.91
Chapter A1.1 --- By lynes --- p.91
Chapter A1.2 --- By lyne pairs --- p.91
Chapter Appendix 2 --- Array Details --- p.92
Chapter A2.1 --- Array of Soli e Duettini for two guitars --- p.92
First Guitar --- p.92
Second Guitar --- p.94
Chapter A2.2 --- Array of Soli e Duettini for flute and guitar --- p.96
Flute --- p.96
Guitar --- p.98
Chapter A2.3 --- Array of Soli e Duettini for violin and viola --- p.100
Violin --- p.100
Viola --- p.102
Chapter Appendix 3 --- Pitch-Class Aggregate Size --- p.104
Chapter A3.1 --- Two-guitar duet --- p.104
Chapter A3.2 --- Flute-guitar duet --- p.105
Chapter A3.3 --- Violin-viola duet --- p.106
Chapter Appendix 4 --- Simultaneity --- p.107
Chapter A4.1 --- Two-guitar duet --- p.107
Chapter A4.2 --- Flute-guitar duet --- p.108
Chapter A4.3 --- Violin-viola duet --- p.108
List of Compositions by Milton Babbitt --- p.109
Unpublished Works --- p.109
Published Works --- p.109
Bibliography --- p.113
Writings of Milton Babbitt --- p.113
Interviews --- p.117
Writings by others --- p.117

碩士
臺北市立大學
教育學系
107
Abstract Based on the publications of Irving Babbitt, this paper aims to understand New Humanism on Babbitt. The purpose of research includes the understanding of Babbitt’s comprehension and criticism of Humanist Tradition in the West, his core values within the New Humanism, how New Humanism on Babbitt became an inspiration in the early years of the Republic of China (ROC) culturally, as well as its educational influence on the country. The research findings are as follow: 1. The thought of the New Humanism on Babbitt inherits the spirt and traditions from the Humanism in the West. 2. The main points of criticism in New Humanism are scientific humanitarianism and sentimental humanitarianism. 3. The four main concepts of New Humanism are “selection”, “discipline”, “classical literature” and “the spirit of leisure”. 4. New Humanism puts emphasis on humanistic spirit and actions taken by humanistic teachers. 5. New Humanism had great influences on the ROC culturally during the country’s early years. 6. From a humanistic viewpoint, New Humanism provides educational implications on the country’s current educational structure and curricular framework. Key words: Irving Babbitt, New Humanism, education

As chumaceiras são exemplos de equipamentos industriais que necessitam de trabalhar juntamente com outras partes móveis para estabelecer movimento relativo entre si. A aplicação de revestimentos nas superfícies das chumaceiras onde existe movimento relativo tem como objetivo alterar as propriedades das superfícies. Os materiais utilizados no revestimento apresentam normalmente uma textura antifricção que permite baixar o coeficiente de atrito, de modo a atenuar o seu desgaste, sendo responsáveis por reduzir paragens frequentes das máquinas, devido à diminuta deformação mecânica que resulta dos movimentos de expansão/contração provocados pelas variações de temperatura. O trabalho apresentado resultou da colaboração com a empresa Cruz & Cruz, com largos anos de experiência no revestimento de chumaceiras e da sua necessidade de aprofundar a compreensão dos mecanismos de adesão que se desenvolvem ao nível da interface substrato/revestimento, contribuindo assim para melhorar a adesão do revestimento à superfície da chumaceira. Neste estudo optou-se por utilizar substratos de aço não ligado com 0,2 % de carbono revestidos com uma liga à base de estanho, designada de metal Babbitt Tego V738. A deposição da liga sobre a superfície da chumaceira foi conseguida pela técnica de fundição por gravidade. Foram caraterizados dois tipos de interface, resultantes de processos distintos de preparação das superfícies dos substratos. A partir de amostras devidamente preparadas foi efetuada uma caraterização microestrutural, através de microscopia ótica e microscopia eletrónica de varrimento, que permitiu estudar os microconstituintes que compõem o aço e o metal Babbitt, junto e afastado da interface. Foram caracterizados os diferentes materiais e identificados os elementos químicos que intervêm no mecanismo de adesão, destacando-se o estanho e o ferro. O efeito da alteração da superfície do substrato foi também avaliado através de ensaios mecânicos, nomeadamente dureza, microdureza e ensaios de tração. Conclui-se desta forma a importância da difusão atómica entre o estanho presente no revestimento e a ferrite presente no substrato, revelando que os substratos devem apresentar na sua microestrutura, principalmente junto da interface, a predominância de fases ricas em ferro. A tensão necessária para separar o revestimento do substrato aumentou quando foi utilizado na preparação da superfície o processo de granalhagem, devido ao efeito da ligação mecânica criada pela existência de reentrâncias.

Trees, as threshold beings, effectively blur the line between the real world and fantastical alternate worlds, and destabilise traditional binary classification systems that distinguish humanity, and Culture, from Nature. Though the presence of trees is often peripheral to the main narrative action, their representation is necessary within the fantasy trope. Their consistent inclusion within fantasy texts of the twentieth century demonstrates an enduring arboreal legacy that cannot be disregarded in its contemporary relevance, whether they are represented individually or in collective forests. The purpose of my dissertation is to conduct a study of various prominent fantasy texts of the twentieth century, including the fantasy works of J.R.R. Tolkien, C.S. Lewis, Robert Holdstock, Diana Wynne Jones, Natalie Babbitt, and J.K. Rowling. In scrutinising these texts, and drawing on insights offered by liminal, ecocritical, ecofeminist, mythological and psychological theorists, I identify the primary function of trees within fantasy narratives as liminal: what Victor Turner identifies as a ‘betwixt and between’ state (1991:95) where binaries are suspended in favour of embracing potentiality. This liminality is constituted by three central dimensions: the ecological, the mythological, and the psychological. Each dimension informs the relationship between the arboreal as grounded in reality, and represented in fantasy. Trees, as literary and cinematic arboreal totems are positioned within fantasy narratives in such a way as to emphasise an underlying call to bio-conservatorship, to enable a connection to a larger scope of cultural expectation, and to act as a means through which human self-awareness is developed.
English Studies
D. Litt. et Phil. (English)