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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

Images fantômes : poétique et modalités esthétiques d'une cinéphilie hantée

Michaud-Lapointe, Alice 08 1900 (has links)
Cette thèse de doctorat se propose de mettre en lumière les liens étroits qui existent entre les imaginaires de la fantomalité, de la hantise et de la cinéphilie contemporaine. Elle cherche à montrer qu’il se développe, depuis le tournant du millénaire, une sous-catégorie de cinéma « à veine cinéphilique », à travers laquelle la figure, à la fois métaphorique et conceptuelle, du fantôme se révèle une instance productrice de discours sur la mémoire du cinéma. Nous cherchons à éclairer la spécificité de cette résurgence de présences fantomales – qui se traduit dans des œuvres cinématographiques, littéraires, critiques et théoriques – et à saisir, dans une perspective esthétique et philosophique, les modalités de hantise qu’elles mettent en scène. L’hypothèse principale de cette recherche s’appuie sur la certitude que cette résurgence de figures fantomales s’inscrit dans une époque instable, marquée par de nombreux bouleversements (politiques, esthétiques, culturels, technologiques), qui l’amène à cultiver une relation surconsciente à la mémoire et à l’amour du cinéma. Pour témoigner de cette tendance et des modalités esthétiques qui la définissent, nous introduisons les concepts de « cinéphilie hantée » et de « hantise cinéphilique ». La première partie de cette thèse analyse les temporalités anachroniques et les logiques cycliques à travers lesquelles les fantômes du cinéma réapparaissent ponctuellement, à l’aune des réflexions de Georges Didi-Huberman, Jacques Derrida, Paul Willemen et Christian Keathley. La deuxième partie s’attache au lieu « catalyseur » de la hantise médiatique : dans quels ancrages ou sites s’immiscent aujourd’hui les présences fantomales qui appellent à repenser la mémoire du cinéma ? Nous étudions quatre cas de figures : le corps de l’acteur Jean-Pierre Léaud, la pellicule filmique en proie à sa désintégration, la salle de cinéma et les variations technologiques contemporaines de la notion de « média hanté » (notamment l’algorithme et le message texte téléphonique). Enfin, dans la troisième et dernière partie de cette thèse, nous observons par quels moyens littéraires ou techniques se déploie cette poétique de « cinéphilie hantée » et quels discours critiques en ressortent. Les œuvres littéraires de Didier Blonde, Jacques Thorens, Nathalie Léger et Jean Paul Civeyrac nous permettent de définir ce qu’est une « écriture hantée » alors que des études portant, entre autres, sur les œuvres de Jean-Luc Godard, Sandi Tan, Frank Beauvais, Nobuhiro Suwa, Pierre Hébert et Guy Maddin nous montrent à quel point le langage cinématographique, dans ses effets formels et techniques, participe intimement de cette écriture de la hantise. En nous penchant sur les questions des temps, des lieux et des manières implicites ou explicites par lesquelles la cinéphilie contemporaine se révèle empreinte de fantomalité, nous cernons les ramifications de cette tendance du cinéma contemporain et en mesurons toute la pertinence. / The aim of this doctoral thesis is to shed light on the close ties between the imaginaries of ghostliness, hauntings and contemporary cinephilia. It seeks to demonstrate that, particularly since the turn of the millennium, a sub-category of cinema “with cinephilic inclinations” has been developing, through which the conceptual metaphor of the ghost reveals itself as a productive instance of discourse on the memory of cinema. Our aim is to elucidate the specificity of this resurgence of ghostly presences—reflected in cinematographic, literary, critical and theoretical works alike—and to grasp, from an aesthetic and philosophical perspective, the modalities of haunting that they stage. The main hypothesis of this research is based on the conviction that the resurgence of ghostly figures is rooted in an unstable era, marked by numerous upheavals (political, aesthetic, cultural, technological), which lead to cultivate an overconscious relationship to the memory and love of cinema. To further demonstrate this tendency and the aesthetic modalities that define it, we introduce in this thesis the “haunted cinephilia” and “cinephilic haunting” concepts. The first part of this thesis analyzes the anachronistic temporalities and cyclical logics through which the ghosts of cinema punctually reappear, in the light of reflections by Georges Didi-Huberman, Jacques Derrida, Paul Willemen and Christian Keathley. The second part focuses on the “catalyst” place of media hauntings: in which anchorages or sites do ghostly presences that call for a rethinking of the memory and love of cinema intrude today? Our research concentrates on four major points: the body of French actor Jean-Pierre Léaud, the disintegrating filmstrip, the movie theatre and the contemporary technological variations of the notion of “haunted media” (particularily the algorithm and the text message). Finally, in the last and third part of the thesis, we examine the literary and technical means by which the poetics of “haunted cinephilia” is deployed, and the critical discourses that emerge from it. We study the literary works of Didier Blonde, Jacques Thorens, Nathalie Léger and Jean Paul Civeyrac to define what constitutes “cinephilic haunted writing”. Studies of the works of Sandi Tan, Frank Beauvais, Jean-Luc Godard, Nobuhiro Suwa, Pierre Hébert and Guy Maddin (among others) also enable us to pinpoint how cinematic language, in its formal and technical effects, can contribute to the development of haunted writing. By examining questions of time, place and the implicit or explicit ways in which cinephilia reveals itself to be permeated with ghostliness, we identify the ramifications of this trend in contemporary cinema and recognize its full scope.
252

Des lanternes magiques aux lyric videos : chansons lumineuses écrites (XIXe – XXIe)

Cauche, Robin 05 1900 (has links)
L’objectif principal de cette thèse est de postuler, pour l’étudier, la série culturelle des « chansons lumineuses écrites », soit une étude diachronique de la pratique consistant à écrire à l’écran les paroles d’une chanson, du XIXe au XXIe siècle. Ce faisant, notre second objectif, d’ordre théorique et méthodologique, est de mettre le concept de « série culturelle », forgé par André Gaudreault et précisé avec l’aide de Philippe Marion (1), à l’épreuve d’un cas particulier, et ainsi d’un ensemble d’exemples. Deux ensembles médiatiques donnent ses bornes chronologiques à la série culturelle : les plaques pour lanterne magique produites et commercialisées par la maison française Lapierre dans la deuxième moitié du XIXe siècle, et les lyric videos, des clips textuels officiels apparus sur YouTube vers 2010. Dans une première partie, on s’intéressera aux « vues sur verre en bande » Lapierre, des plaques de verre peintes à la main destinées à la projection domestique et illustrant des sujets populaires, dont des chansons. On documentera d’abord le fonctionnement des lanternes magiques en général et des séries de plaques commercialisées par les Lapierre en particulier, dans le but d’en proposer une méthode d’analyse esthétique pertinente. En retour, ce modèle pourra être éprouvé en s’appuyant sur le corpus spécifique des chansons illustrées Lapierre. Dans la deuxième partie, on montrera que la pratique des chansons écrites à l’écran ne disparaît pas au XXe siècle, et qu’une série culturelle se forme bel et bien, du XIXe au XXIe siècle. On s’intéressera donc à l’apparition des chansons lumineuses écrites selon trois types de médiums : lanterne de projection, pellicule cinématographique et vidéo. Par un dernier chapitre précisément consacré aux bouncing balls, on prouvera la permanence de notre série culturelle, sur le temps long et par-delà les médiums. Dans la troisième et dernière partie, on se penchera sur l’émergence des lyric videos, des clips officiels apparus vers 2010 sur YouTube, et illustrant surtout des chansons pop. Deux chapitres théoriques s’attacheront d’abord à révéler comment les lyric videos forcent à reconsidérer la théorie, l’histoire et l’esthétique des clips à l’ère de YouTube et des plateformes numériques. Trois chapitres s’efforceront ensuite de décrire et de comprendre le vaste corpus des lyric videos grâce à des approches comparative, générique puis génétique. (1) Voir par exemple : André Gaudreault et Philippe Marion, « Défense et illustration de la notion de série culturelle », dans A History of Cinema without Names. A Research Project, sous la direction de Diego Cavalotti, Federico Giordano, et Leonardo Quaresima (Udine : Mimesis, 2016), 60. / The main goal of this thesis is to examine a cultural series that we designate as “chansons lumineuses écrites” (“written luminoussongs”), hence producing a diachronic study of the cultural practice of writing the lyrics of a song on screen, from the 19th to the 21st century. In doing so, our second goal – of a theoretical and methodological nature – is to put the concept of “cultural series,” created by André Gaudreault and refined with the help of Philippe Marion1, to the test of a case study, while working with a set of relevant examples. Two sets of examples give this cultural series its chronological boundaries: the magic lantern slides produced and marketed by the French firm Lapierre, in the second half of the 19th century, and lyric videos, official textual music videos which appeared on YouTube around 2010. In the first section of this thesis, we will focus on the Lapierre “vues sur verre en bande” (“glass views in strips”), hand-painted glass slides intended for domestic projection which illustrate popular subjects, including songs. We will document the technical functioning of magic lanterns in general and the series of slides marketed by the Lapierre firm in particular, to propose a relevant method of aesthetic analysis of these slides. In turn, we will put this method to the test as we examine the corpus of the Lapierre illustrated songs. In the second section, we will show that the practice of writing song lyrics on screen did not disappear in the 20th century, and that a cultural series exists, from the 19th to the 21st century. We will then focus on three types of medium: magic lantern, film, and video. A fourth chapter will discuss the particular practice of the bouncing ball and, through this example, we will prove the permanence of our cultural series, over the long term, and beyond changes of medium. The third and final part of this work will examine the emergence of lyric videos, official music videos which started appearing around 2010 on YouTube, illustrating mostly pop songs. Two theoretical chapters will first discuss how lyric videos force us to reconsider the theory, history and aesthetics of music videos in the era of YouTube and digital platforms. Three chapters will then attempt to describe and understand the vast corpus of lyric videos, using comparative, generic and genetic approaches.
253

Les gestes du patenteux au cinéma et en arts sonores : vocalises et ex-tension des haut-parleurs

Campeau, Emmanuel 08 1900 (has links)
Mémoire en recherche-création / Ce mémoire de recherche-création explore un geste inspiré d’une dimension de l’art sonore, soit celui d’ex-tensionner les haut-parleurs (Gallet 2007). Il mobilise le patentage, c’est-à-dire une posture artistique qui interagit directement avec les objets d’ingénierie. Le patenteux, figure emblématique du territoire et de la culture québécoise, se réclame de ce dialogue entre geste de création et recherche ingénieuse. La première partie de cet ouvrage se dévoue à la cartographie de ce champ de pratique, à l’aide des origines linguistiques du mot patente, à l’aide des différentes rémanences culturelles et historiques des patenteux, à l’aide de la figure du bricoleur de Lévi-Strauss ainsi qu’à l’aide de la notion d’indiscipline. La seconde partie se penche sur l’application de cette pratique à la création sonore et au cinéma. Le patentage se révèle ainsi une façon de trouver, sinon prêter une voix aux haut-parleurs, qui deviennent alors des œuvres-machines. Appliqué au cinéma, c’est une façon d’en altérer et redéfinir les paramètres d’écoute. Ces conséquences sont mises en exergue dans un quintette de patentes présentées à l’aide de similibrevets, aussi incarnées dans une installation audiovisuelle. / This research-creation thesis explores a gesture inspired by a facet of sound art, specifically the act of extending speakers (Gallet 2007). It employs patentage, an artistic approach that directly engages with engineering objects. The patenteux, a distinctive figure in Quebec's culture and territory, represents this interaction between creative acts and inventive research. The first part of the thesis maps this field of practice, examining the linguistic origins of the word patente, the cultural and historical resonances of the patenteux, Lévi-Strauss’s concept of the thinkerer, and the idea of indiscipline. The second part applies this approach to sound creation and cinema. Patentage thus offers a way to either discover or bestow a voice upon speakers, transforming them into works-machines. In cinema, it provides a means to alter and redefine listening parameters. These effects are showcased in a quintet of mock patents and embodied in an audiovisual installation.
254

Male Bodies On-Screen: Spectacle, Affect, and the Most Popular Action Adventure Films in the 1980s

Wagenheim, Christopher Paul, Ph.D. 07 December 2016 (has links)
No description available.
255

Mascelli's functional analysis of camera angles versus viewers' interpretations of unconventional camera angles in Avatar and The English Patient / Carli Uys

Uys, Carli January 2014 (has links)
The primary research strategy of this study was to elicit meaningful answers from viewers by means of a focus-group procedure; this is a method associated with qualitative research (see Creswell, 1998; Berg & Lune, 2011) The group consisted of ten adults, whose visual literacy in terms of narrative films, was described as high (they frequently watch films at home, or in the theatre). The researcher acted as the moderator; and a set of semi-structured questions, based on meanings attached to camera-angle codes as defined by Mascelli, were answered by the participants. The codification scheme of Mascelli was applied to the unconventional camera angles in Avatar and The English Patient. These were compared with the viewers’ responses. Finally, the results were interpreted, in order to establish whether a meaningful relationship exists between the viewers’ responses and the interpretation of unconventional camera angles by such a seminal figure as Joseph V. Mascelli. The literature study focused on a media aesthetic explanation of cinematography, which included media aesthetics theory, framing, and composition, as well as the general codes and conventions relevant to cinematography. The literature overview includes a study of books, academic articles, internet sources, legislation, and training videos. A Nexus and EbscoHost search (Academic Search Premier and Jstor) was conducted on cinematography in general, and on camera angles in particular. Chapter 5 indicates the viewers’ overall interpretations of the unconventional camera angles used in Avatar and The English Patient. The graphs in Chapter 5 indicate that the viewers found the unconventional camera angles used in the films to represent the meaning of the shots appropriately, and that they understood why each unconventional camera angle had been used. The viewers’ responses correspond with the meanings of the unconventional camera angles, as stated by Mascelli. To ensure the effectiveness of a film and the accurate representation of the meanings of camera angles and camera sizes, the way it is described by Mascelli should ideally be taken into consideration by all future producers. Mascelli’s descriptions of camera angles and camera sizes, combined with the media aesthetics, as described by Zettl – when successfully applied – could lead to the production of a good quality film and images within the film. / MA (Communication Studies), North-West University, Potchefstroom Campus, 2014
256

Mascelli's functional analysis of camera angles versus viewers' interpretations of unconventional camera angles in Avatar and The English Patient / Carli Uys

Uys, Carli January 2014 (has links)
The primary research strategy of this study was to elicit meaningful answers from viewers by means of a focus-group procedure; this is a method associated with qualitative research (see Creswell, 1998; Berg & Lune, 2011) The group consisted of ten adults, whose visual literacy in terms of narrative films, was described as high (they frequently watch films at home, or in the theatre). The researcher acted as the moderator; and a set of semi-structured questions, based on meanings attached to camera-angle codes as defined by Mascelli, were answered by the participants. The codification scheme of Mascelli was applied to the unconventional camera angles in Avatar and The English Patient. These were compared with the viewers’ responses. Finally, the results were interpreted, in order to establish whether a meaningful relationship exists between the viewers’ responses and the interpretation of unconventional camera angles by such a seminal figure as Joseph V. Mascelli. The literature study focused on a media aesthetic explanation of cinematography, which included media aesthetics theory, framing, and composition, as well as the general codes and conventions relevant to cinematography. The literature overview includes a study of books, academic articles, internet sources, legislation, and training videos. A Nexus and EbscoHost search (Academic Search Premier and Jstor) was conducted on cinematography in general, and on camera angles in particular. Chapter 5 indicates the viewers’ overall interpretations of the unconventional camera angles used in Avatar and The English Patient. The graphs in Chapter 5 indicate that the viewers found the unconventional camera angles used in the films to represent the meaning of the shots appropriately, and that they understood why each unconventional camera angle had been used. The viewers’ responses correspond with the meanings of the unconventional camera angles, as stated by Mascelli. To ensure the effectiveness of a film and the accurate representation of the meanings of camera angles and camera sizes, the way it is described by Mascelli should ideally be taken into consideration by all future producers. Mascelli’s descriptions of camera angles and camera sizes, combined with the media aesthetics, as described by Zettl – when successfully applied – could lead to the production of a good quality film and images within the film. / MA (Communication Studies), North-West University, Potchefstroom Campus, 2014
257

Les impacts de la démocratisation sur un secteur culturel : le cinéma sud-africain post-apartheid / Impacts of democratization on a cultural sector : the post-apartheid South African cinema

Landau, Gallaye-Joachim 04 July 2012 (has links)
Cette thèse met en avant, d’une part, les bouleversements qui parcourent le secteur cinématographique en Afrique du Sud depuis 1994 : volontés d’autonomie esthétique et économique, recherches de voix authentiques, formation d’une nouvelle famille de cinéastes.D’autre part, cette recherche révèle le rôle de l’État Sud-Africain dans la définition de la fonction du cinéma au sein de la démocratie contemporaine : Organes spécialisés de l’État, politiques publiques, idéologies, relations avec les professionnels du secteur. / This thesis highlights on one hand, changes that run through the film industry in South Africa since 1994 : wills of aesthetic autonomy and economic, research of authentic voices, growth of a new family of filmmakers. Moreover, this research reveals the role of government in the South African definition of the function of cinema in the contemporary democracy: specialized organs of the State, public policies, ideologies, relationships with industry professionals.
258

Realita v československých kriminálních filmech z 60. let (s důrazem na postavu vyšetřovatele a kriminalistické metody) / Realism in the Czechoslovak crime films from 60's (with the emphasis on the figure of criminalist and criminalistic methods)

Staňková, Nikola January 2019 (has links)
Films and series with criminal themes are very popular among audience. They also have quite a long tradition in the Czech (Czechoslovak) cinematography. Specifically in the 60's a lot of quality films with detective plots were made and they are appreciated among the audience until today. They are also repeated in television frequently. These films demonstrate both crime and further investigation, focused on the police activity. This representation is frequently portrayed as a reality and the audience tend to view it as such. Therefore, it is interesting to observe if this representation corresponds to real forensic practice. This diploma thesis deals with the given matter. It analyses five Czechoslovak crime films from the 60's and its goal is to determine if the forensic methods correspond to then reality. It also focuses on the figure of the investigator as the representative of the law and as the main character. The first part of the thesis is comprised of the theoretical background. It describes the principles of film narrathology and mainly the principles of forensic methodology and practice. The second part of the thesis is practical. The theoretical background is applied here to analyse each of the chosen films. The summary responds to the research question and summarizes results of the analysis.
259

Criança, narrativa e amor: os vínculos afetivos em Sakura Card Captors

Santilli, Ana Catarina 13 June 2018 (has links)
Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2018-08-01T11:32:14Z No. of bitstreams: 1 Ana Catarina Santilli.pdf: 5124968 bytes, checksum: 853c02ce314ebf3095abfe8148ec5c20 (MD5) / Made available in DSpace on 2018-08-01T11:32:14Z (GMT). No. of bitstreams: 1 Ana Catarina Santilli.pdf: 5124968 bytes, checksum: 853c02ce314ebf3095abfe8148ec5c20 (MD5) Previous issue date: 2018-06-13 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / According to Jerusa Pires Ferreira’ studies, popular myths and tales always had a great role in the storage and transmission of elements of a culture. However, due to parents' lack of time, there is no longer a tradition of telling stories to children, and the main sources of these stories end up being the audio-visual animations shown on children's channels or on internet video sites. The problem is, as Norval Baitello Júnior and Vicente Romano noticed, more and more people relate to media images and stop being connected with other bodies, which can decrease sensitivity to deal with others. This becomes more alarming when we realize the contents produced for children, who are in a formation phase, in which they most need affection. From a research by Jo Groebel, it was noticed that children turn to media heroes as role models to help them cope with difficult situations. However, many of these heroes resolve their conflicts aggressively, and pass on the message that there are bad people who should be eliminated, which often generates tension and anxiety. From there, this research has an interest to study how a children's audiovisual narrative can treat love in a way that sensitizes the child to the other and to the important gestures in human bonding. In this case, love is understood as a personal bond that unites one human being to another. For this purpose, the animation Sakura Card Captors was chosen as the study corpus. It is a Japanese children's cartoon, appeared in Brazil in the early 2000s, and it was very successful among the public. It is a narrative that explores a great variety of affective bonds between the characters, in many scenes of banal moments, but in which the small gestures used to deal with the others are perceptible. Starting from the works of the ethologists Boris Cyrulnik and Irenäus Eibl-Eibesfeldt about love, and from the studies of the infant psychoanalyst Bruno Bettelheim on narratives for children, this research intends to throw a phenomenological view on the object, making an analysis of the narrative from the links between the characters. The intention is to check the types of love present in the cartoon, according to the classification of affective systems made by Harry Harlow, and to observe how the characters affect each other during the story. It was interesting to note that the animation is able to explore a series of bonds that children form during their lives, emphasizing some daily life details important to the connection with people and the world / Segundo os estudos da Prof.ª Dr.ª Jerusa Pires Ferreira, percebe-se que os mitos e contos populares sempre tiveram um grande papel no armazenamento e na transmissão de elementos de uma cultura. Contudo, com a falta de tempo dos pais, há uma perda da tradição de se contar histórias para os filhos, e as principais fontes de narrativas para as crianças acabam sendo as animações audiovisuais, exibidas em canais infantis ou em sites de vídeo da Internet. O problema é que cada vez mais as pessoas se relacionam com imagens midiáticas e menos se vinculam a outros corpos, o que pode diminuir a sensibilidade no trato com o outro, como alertam Norval Baitello Júnior e Vicente Romano. Isso se torna mais preocupante quando se pensa nos conteúdos produzidos para as crianças, que estão em fase de formação, em que mais precisam de afeto. Pelas pesquisas realizadas por Jo Groebel, foi possível notar que as crianças recorrem aos heróis da mídia como modelos que as auxiliam a lidar com situações difíceis. No entanto, muitos desses heróis resolvem seus conflitos de forma agressiva e passam a mensagem de que existem pessoas más que devem ser eliminadas, o que costuma gerar tensão e ansiedade. A partir daí, a pesquisa buscou estudar como uma narrativa audiovisual infantil, ao invés de estimular a agressão, pode fomentar o amor. Nesse caso, o amor é entendido como vínculo afetivo que une um ser humano ao outro. Ou seja, a proposta foi estudar como uma animação pode tratar o amor de forma que sensibilize a criança ao outro e aos gestos importantes na relação humana. Para tal foi escolhida como corpus de estudo a animação Sakura Card Captors, uma série japonesa infantil, exibida no Brasil no início dos anos 2000 e que teve muito sucesso entre o público. Trata-se de uma narrativa que explora uma grande variedade de vínculos afetivos entre as personagens, em muitas cenas de momentos banais, mas nas quais são perceptíveis os pequenos gestos utilizados no trato com o próximo. Partindo das obras dos etólogos Bóris Cyrulnik e Irenäus Eibl-Eibesfeldt sobre o amor e dos estudos do psicanalista infantil Bruno Bettelheim sobre narrativas para crianças, a pesquisa lançou um olhar fenomenológico sobre o objeto, realizando uma análise da narrativa a partir dos vínculos entre as personagens. A intenção foi verificar os tipos de amor presentes no desenho, de acordo com a classificação de sistemas afetivos feita por Harry Harlow, e observar como as personagens se afetam durante a história. Foi interessante notar que a animação consegue explorar diversos vínculos que a criança forma durante a vida, dando ênfase a detalhes do cotidiano importantes para se conectar às pessoas e ao mundo
260

Contribution à l'étude de la transition décharge luminescente / arc électrique dans l'air et dans l'argon au voisinage de la pression atmosphérique. / Contribution to the study of the transition between glow discharges and electric arcs in air and in argon near atmospheric pressure

Landfried, Romaric 06 December 2011 (has links)
Dans ce travail, nous proposons une approche essentiellement expérimentale. Dans une première partie, nous exposons les résultats obtenus par imagerie rapide et mesures électriques corrélées dans le temps, concernant l’étude de la transition entre des électrodes de cuivre dans l’air et l’argon, et entre des électrodes de tungstène dans l’argon pour des pressions comprises entre 100 mbar et 1 bar. Dans aucun cas une transition à l’arc n’est observée sans constriction quasi-totale de la colonne positive. Dans le cas d’électrodes en tungstène dans l’argon, la vitesse d’extension de la zone filamentaire depuis l’anode vers la cathode a été vue dépendante de la pression et de l’intensité. La durée d’une transition spontanée a été linéairement corrélée à la distance inter-électrode, suggérant un mécanisme propagatif à vitesse constante dans la colonne. Plus la pression est élevée, plus la durée totale des transitions est longue ; par ailleurs, à pression constante, cette durée de transition spontanée décroît à intensité croissante, pour tendre vers une durée limite, correspondant à la durée constante de changement de structure de la zone cathodique. Dans une seconde partie, nous nous intéressons à l’échauffement de surfaces d’anodes et de cathodes en cuivre dans l’air et dans l’argon soumises à des arcs électrique pour plusieurs gammes de courant (de 30 à 120 A). Deux méthodes de mesures sont utilisées. Enfin, nous utilisons les mesures de températures de surface pour proposer deux modèles simples de bilan de puissance à la surface des électrodes (flux de chaleur). L’un considère uniquement le chauffage dû au spot d’arc et l’autre le chauffage supplémentaire de la colonne d’arc. / In this work, an approach which is essentially experimental is proposed. In the first part, results are presented which were obtained by synchronized fast camera imaging and electrical measurements. These concern the study of the transition between copper electrodes in air and in argon, and between tungsten electrodes in argon for gas pressure in the range 100 mbar – 1 bar. In no case was the transition to arc been observed without the quasi-total constriction of the positive column. Considering tungsten electrodes in argon, the propagation speed of the filamentary part of the positive column from the anode to the cathode was found to be dependent on the gas pressure and the discharge current intensity. During spontaneous transition, the transition duration has been linearly correlated to the electrode gap, suggesting a propagative mechanism with a constant speed. The higher the pressure, the longer is the total transition duration. For a constant pressure and discharge current, the duration of spontaneous transition decreases with decreasing gap distance toward a limiting value, which corresponds to the constant duration of the structural change of the cathode root from diffuse to spot. In the second part, heating of copper anodes and copper cathodes submitted to electric arcs in air and in argon and for various current intensity values (from 30A to 120 A) is considered. Two measurement methods are used. Finally, the surface temperature measurements are used to purpose two models of the electrode surface power balance (heat flux). One model only considers the heating due to the arc spot and the second one considers a supplementary heating from the arc column.

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