962 resultados para Joan, of Arc, Saint, 1412-1431.
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A torch with a set of inter-electrode inserts between the cathode and the anode/nozzle with a wide nozzle exit was designed to generate plasma jets at chamber pressures of 500–10 000 Pa. The variation of the arc voltage was examined with the change in working parameters such as gas flow rate and chamber pressure. The fluctuation in the arc voltage was recorded with an oscilloscope, and the plasma jet fluctuation near the torch exit was observed with a high-speed video camera and detected with a double-electrostatic probe. Results show that the 300 Hz wave originated from the tri-phase rectified power supply was always detected under all generating conditions. Helmholtz oscillations over 3000 Hz was detected superposed on the 300 Hz wave at gas flow rates higher than 8.8 slm with a peak to valley amplitude lower than 5% of the average voltage value. No appreciable voltage fluctuation caused by the irregular arc root movement is detected, and mechanisms for the arc voltage and jet flow fluctuations are discussed.
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Arc root behavior affects the energy transfer and nozzle erosion in an arcjet thruster. To investigate the development of arc root attachment in 1 kW class N2 and H2-N2 arcjet thrusters from the time of ignition to the stably working condition, a kinetic series of end-on view images of the nozzle obtained by a high-speed video camera was analyzed. The addition of hydrogen leads to higher arc voltage levels and the determining factor for the mode of arc root attachment was found to be the nozzle temperature. At lower nozzle temperatures, constricted type attachment with unstable motions of the arc root was observed, while a fully diffused and stable arc root was observed at elevated nozzle temperatures.
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In the last few years there has been much discussion as to the relative merits or arc welded joints as compared to riveted joints. There is an old precedent which must be removed before arc welding will come into its own. The purpose of this paper is to help establish confidence in this process of fabrication with special regard to strength and reliability.
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This thesis examines the late seventh-century Latin Life of Columba (Vita Columbae) in a context sympathetic to the spiritual aims and formative intellectual background of its author, Adomnán of Iona. It argues that the Vita Columbae is a sophisticated work, shaped by Adomnán’s spiritual and theological concerns. This sophistication is revealed by a forensic examination of Adomnán’s representation of Columba’s sanctity through a series of miracles, in particular, miracle stories depicting divine manifestations of fire and light. This thesis considers the form and function of these miracle stories in the context of biblical, patristic and medieval interpretations of their archetypes, towards revealing the underlying influence of scriptural, hagiographical and monastic models of sanctity. Chapter one evaluates the function of the Vita Columbae, and outlines the core themes of sanctity which pervade the work, by considering the technical terminology and literary devices found in the opening prefaces in the context of the wider monastic tradition. Chapter two examines Adomnán’s use of biblical models of sanctity to establish Columba’s sanctity, and their relationship between these models and certain miraculous episodes in the Vita Columbae. Chapter three investigates Adomnán’s description of the Holy Spirit as an illuminating fire, and its significance for his portrayal of the saint, by means of a forensic examination of biblical, exegetical and hagiographical treatments of the image. Chapter four examines the missiological, soteriological and providential elements contributing to Adomnán’s portrayal of Columba’s sanctity, as conveyed through the presence of biblical models, particularly the image of the column of fire. Chapter five establishes the influence of monastic examinations of the contemplative life on Adomnán’s portrayal of Columba’s sanctity, and shows how that sanctity is confirmed in terms of his ability to contemplate divine light.
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Throughout his long and industrious lifetime, Camille Saint-Saens (1835-1921) devoted himself unconditionally to music both as a composer and a performer. Saint-Saens was a self-described traditionalist and musical purist, yet his works are distinctly expressive and imaginative, and they reflect the composer's own unique musical language which incorporates recognizably modem traits such as chromaticism and frequent modulation. As a performer, Saint-Saens preferred to premiere his own works and often included his chamber music in his concert programs. Regarded primarily as a symphonic composer in the present day, however, his extensive and varied collection of chamber music works is sadly neglected. Six varied small-ensemble works with piano from his chamber music repertoire have been selected for study and recording for this project: Piano Trio No. 1 in F Major, Op. 18 (1864); Sonata for Cello and Piano No. 1 inC Minor, Op. 32 (1872); two pieces for two pianos, Le Rouet d'Omphale (The Spinning Wheel ofOmphale), Op. 31 (1871) and Phaeton, Op. 39 (1874); piano duet Konig Harald Haifagar (King Harald Haarfager), Op. 59 (1880); and a wind quartet, Caprice sur des airs Danois et Russes (Caprice on Danish and Russian Airs) for Flute, Oboe, Clarinet and Piano, Op. 79 (1887). Analyses of the forms and harmonic structures of these compositions will be included in this dissertation paper as well as studies from the viewpoint of Saint-Saens' compositional style, ensemble characteristics, and writing for the piano. The recordings for this project were made in four sessions in LeFrak Concert Hall at Queens College, the City University of New York. On September 24, 2003, Op. 31, Op. 39 and Op. 59 were recorded with Professor Morey Ritt, piano. On March 2, 2004, Op. 18 was recorded with Elena Rojas, violin, and Clare Liu, cello, and on March 15, 2004, Op. 32 was recorded, also with Ms. Liu. The Caprice, Op. 79 was recorded on June 27, 2008 with Laura Conwesser, flute; Randall Wolfgang, oboe; and Steve Hartman, clarinet. The recordings may be found on file in the library at the University of Maryland, College Park.
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The arc-length method has become a widely established solution technique for studying nonlinear structural behavior. By augmenting the set of nonlinear equilibrium equations with a constraint equation, which is a function of both the displacements and load increment, it is capable of traversing limit points. Numerous investigations have shown that highly nonlinear behavior such as sharp "snap-backs" can still lead to numerical difficulties. Two practical examples are presented to assess the effectiveness of this solution technique in capturing secondary instabilities in postbuckling structures, which present themselves as abrupt mode jumps. Although the first example poses no special difficulties, in the second case the nonlinear procedure fails to converge. An improvement to the method's formulation is suggested, which accounts for the residual forces that are usually neglected, when proceeding to the next increment once convergence is reached on the current increment. The choice of a correct load increment at the first iteration, within a predictor-corrector scheme, is central to the method's effectiveness. Current strategies for a choice of this load increment are discussed and are shown to be no longer consistent with the modified formulation; therefore, a new approach is proposed.
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Référence bibliographique : Rol, 59182
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Référence bibliographique : Rol, 59183
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Référence bibliographique : Rol, 59184
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Référence bibliographique : Rol, 59186
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Référence bibliographique : Rol, 59190
