Dissertationen zum Thema „Fusion à arc“
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Geneste, Gilles. „Une application de l'arc électrique : les fours à arcs de fusion en courant alternatif“. Paris 5, 1989. http://www.theses.fr/1989PA05P106.
Der volle Inhalt der QuelleIordache, Luminita. „Analyse tribo-métallurgique des rechargements base cobalt par fusion soudage d'outillages à chaud“. Paris, ENSAM, 2006. http://www.theses.fr/2006ENAM0065.
Der volle Inhalt der QuelleCerqueira, Nuno. „Fusion de résidus minéraux par arc électrique : Comportement des métaux lourds“. Limoges, 2002. http://www.theses.fr/2002LIMO0053.
Der volle Inhalt der QuelleThis work is devoted to the study of heavy metals behavior during arc plasma vitrification of fly ash. In the first part, the fate of heavy metals during incineration of domestic wastes is followed; physicochemical properties of fly-ash and the process - especially vitrification - to stabilize and to solidify this hazardous waste are presented with special attention to long-term containment quality. In the second part, the experimental set-up is described: a crucible, filled with synthetic fly-ash in which metallic salts and oxides are added, is set in the coupling zone of plasma arc transferred between two bipolar electrodes. Metallic vapours densities in the gaseous phase above the melt surface are measured by optical emission spectroscopy. In this chapter, is also briefly presented the mass spectrometric analysis of the exhaust gases. In the third chapter, a model to predict the evaporation of some heavy metals, of chlorine and of sulfur, from the melt is presented: the influence of the chlorine content in the chemical mixture to be vitrified and also the influence of the oxygen partial pressure in the gaseous phase are studied; finally the progressive heating of the system is considered. In the last chapter, for Pb, Cd, Zn and Cr, the experimental results are gathered in front of the modeling ones. The influences of the oxygen partial pressure in the gaseous phase and of chlorine content of the melt are enlightened
Shen, Hao. „Seam position detection in pulsed gas metal arc welding“. Access electronically, 2003. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20040823.125740/index.html.
Der volle Inhalt der QuelleDean, Gary. „Optimization of metal transfer and fusion using current control in dip transfer GMAW“. Access electronically, 2003. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20041029.140918/index.html.
Der volle Inhalt der QuelleLe, Guen Émilie. „Étude du procédé de soudage hybride laser/MAG : caractérisation de la géométrie et de l’hydrodynamique du bain de fusion et développement d’un modèle 3D thermique“. Lorient, 2010. https://tel.archives-ouvertes.fr/tel-00546986.
Der volle Inhalt der QuelleHybrid laser/MIG-MAG welding shows high advantages compared to laser welding or GMAW arc welding used separately. Thanks to this process, higher productivity can be gained through higher welding speed, higher squeeze tolerance moreover possible improvement of the metallurgical properties of the weld seam can be obtained. However, many operating parameters have to be set up in order to achieve optimal process. The complex physical phenomena, which govern welding process, have to be understood in order to use efficiently this technique in mass production. Understanding of these phenomena is also necessary to program numerical simulations which fit to this process. In the first step, experimental studies have been carried out with GMAW, laser and hybrid welding on samples of S355 steel. Influence of operating parameters has been analyzed through films performed with speed camera and macrographies of weld seam cross section. Surface deformations of the melt pool, induced by the arc pressure, weld pool length, droplet detachment and welding speed, have been analyzed precisely from images of the surface melt pool. In a second step, a numerical model was developed using the COMSOL Multiphysics® software for MAG, laser and hybrid laser/MAG welding processes. A 3D quasi-stationary model has been calculated from the temperature field within the metal. The originality of the MAG and hybrid model lies in the prediction of the melt pool surface profile used to determine the 3D geometry, by taking into account the material input The influence of different parameters such as arc power and speed welding on the efficiency as well as the distribution radius of the arc power and the arc pressure are analyzed through validations with different experimental results and different calculation configurations
Li, Peigang. „Cold lap formation in Gas Metal Arc Welding of steel : An experimental study of micro-lack of fusion defects“. Doctoral thesis, Högskolan Väst, Avd för maskinteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-5596.
Der volle Inhalt der QuelleOla, Oyedele. „A study of laser-arc hybrid weldability of nickel-base INCONEL 738 LC superalloy“. Materials Science and Technology, 2013. http://hdl.handle.net/1993/22076.
Der volle Inhalt der QuellePereira, Luiz Alberto Tavares. „Desenvolvimento de processos de reciclagem de cavacos de Zircaloy via refusão em forno elétrico a arco e metalurgia do pó“. Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-27052014-090225/.
Der volle Inhalt der QuellePWR reactors employ, as nuclear fuel, UO2 pellets with Zircaloy clad. In the fabrication of fuel element parts, machining chips from the alloys are generated. As the Zircaloy chips cannot be discarded as ordinary metallic waste, the recycling of this material is important for the Brazilian Nuclear Policy, which targets the reprocess of Zircaloy residues for economic and environmental aspects. This work presents two methods developed in order to recycle Zircaloy chips. In one of the methods, Zircaloy machining chips were refused using an electric-arc furnace to obtain small laboratory ingots. The second one uses powder metallurgy techniques, where the chips were submitted to hydriding process and the resulting material was milled, isostatically pressed and vacuum sintered. The ingots were heat-treated by vacuum annealing. The microstructures resulting from both processing methods were characterized using optical and scanning electron microscopies. Chemical composition, crystal phases and hardness were also determined. The results showed that the composition of recycled Zircaloy comply with the chemical specifications and presented adequate microstructure for nuclear use. The good results of the powder metallurgy method suggest the possibility of producing small parts, like cladding end-caps, using near net shape sintering.
Wang, Fei. „Study of radiative properties : application to fast determination of temperature and iron concentration for MAG-P Arc (Ar-CO2-Fe mixtures) and to estimation of photobiological hazards for argon GTAW Arc“. Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30121/document.
Der volle Inhalt der QuelleThis PhD thesis introduces a method that allows the fast determination of temperature and iron concentration for MAG-P Arc. The MAG-P Arc is in fact [Ar-CO2]-Fe mixtures, with a constant molar ratio between Ar and CO2 [82%Ar-18%CO2]. In a second time, this thesis presents a study of the optical radiation associated to photobiological hazards for argon GTAW Arc. In chapter 1, the background and motivation of this work is introduced. The previous works published in this field are reviewed. In chapter 2, the equilibrium compositions are calculated firstly using the minimization of Gibbs free energy. Then the radiative properties of [Ar-CO2]-Fe plasmas are obtained in the frame of the net emission coefficient (NEC) approach, using the accurate "line by line" method. All significant radiative contribution mechanisms are taken into account in the calculation. This study will constitute a groundwork to build the diagnostic method that allows determination of temperature and iron concentration profiles in welding arc. In chapter 3, spectroscopic investigation of the LTE hypothesis across the MAG-P Arc is made. Excitation temperature is obtained with Boltzmann plot method while iron and argon lines Stark broadening measurements are used to get electron temperature and electron density. LTE hypothesis validity across the arc is discussed considering the agreement between the two temperatures, the electron density and iron content. Results show supporting evidence for the main part of the plasma, along radial and axial directions. Discrepancies occur only at the fringe of the arc, where the two temperatures differ by more than 2000 K. In chapter 4, a method allowing a fast determination of space- and time-resolved plasma temperature and iron concentration in MAG arcs during the high-current phase is introduced. This method consists in measuring the plasma spectral radiation of the arc with iron vapours using a high-speed camera filtered by narrow band filters in the spectral intervals of 570-590 nm and 606-627 nm respectively; calculating theoretically the dependence of the absolute emissivity e570-590 nm and relative emissivity e570-590 nm/e607-627 nm versus the plasma temperature and the iron concentration. This method has also been validated for a layer of plasma by adopting other existing diagnostics such as Stark broadening, which demonstrates the effectiveness of this new method. In chapter 5, a theoretical investigation of the UV (180-400 nm), UVA (315-400 nm) and blue light (300-700 nm) radiation associated with the photobiological hazards to workers for argon GTAW arcs is presented. The radiative properties of argon plasma are calculated for the three spectral regions, and a two-dimensional model of a GTAW arc is then developed to determine the local emissions in the arc, the total radiation escaping from the arc and corresponding effective irradiances. This study clearly supports the importance of undertaking an effective protection strategy for workers, particularly for skin and eyes, in the welding environment. Finally, a general conculsion is given in chapter 6
Moradi, Sara. „Transport analysis in tokamak plasmas“. Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210097.
Der volle Inhalt der QuelleOne of the least understood areas of the impurity transport and indeed any plasma particle or heat transport in general, is the turbulent transport. Extensive efforts of the fusion plasma community are focused on the subject of turbulent transport. Motivated by the fact that impurity transport is an important issue for the whole community and it is an area which needs fundamental research, we focused our attention on the development of turbulent transport models for impurities and their examination against experiments. In a collaboration effort together with colleagues (theoreticians as well as experimentalist) from different research institutes, we tried to find, through our models, physical mechanisms responsible for experimental observations. Although our main focus in this thesis has been on the impurity transport, we also tried a fresh challenge, and started looking at the problem of drift wave turbulent transport in a different framework all together. Experimental observation of the edge turbulence in the fusion devices show that in the Scrape of Layer (SOL: the layer between last closed magnetic surface and machine walls) plasma is characterized with non-Gaussian statistics and non-Maxwellian Probability Distribution Function (PDF). It has been recognized that the nature of cross-field transport trough the SOL is dominated by turbulence with a significant ballistic or non-local component and it is not simply a diffusive process. There are studies of the SOL turbulent transport using the 2-D fluid descriptions or based on probabilistic models using the Levy statistics (fractional derivatives in space). However, these models are base on the fluid assumptions which is in contradiction with the non-Maxwellian plasmas observed. Therefore, we tried to make a more fundamental study by looking at the effect of the non-Maxwellian plasma on the turbulent transport using a gyro-kinetic formalism. We considered the application of fractional kinetics to plasma physics. This approach, classical indeed, is new in its application. Our aim was to study the effects of a non-Gaussian statistics on the characteristic of the drift waves in fusion plasmas.
Ce travail de thèse porte sur le transport turbulent d'impuretés dans les plasmas de fusion
par confinement magnétique. C'est une question de la plus haute importance pour le développement
de la fusion comme source d'énergie. En effet, une accumulation d'impuretés au coeur
du plasma impliquerait des pertes d'énergie par radiation, conduisant par refroidissement à
l'extinction des réactions de fusion. Il est par contre prévu d'injecter des impuretés dans le
bord du plasma, afin d'extraire la chaleur par rayonnement sans endommager les éléments de
la première paroi. Ces contraintes contradictoires nécessitent un contrôle précis du transport
d'impuretés, afin de minimiser la concentration d'impuretés au coeur du plasma tout en la
maximisant au bord. Une très bonne connaissance de la physique sous-jacente au transport
est donc indispensable. L'effet de la turbulence, principal mécanisme de transport, sur les impuretés
est alors une question centrale. Dans cette thèse, un code numérique, AFC-FL, a été développé sur la base d'une approche ``fluide' linéaire pour la turbulence d'ondes de dérive. Il calcule les taux de croissance qui caractérisent la rapidité de l'amorçage des instabilités. L'analyse de stabilité est complétée par l'évaluation des taux de croissance en présence d'un gradient de densité, un cisaillement magnétique ou un nombre arbitraire de différentes espèces d'impureté. Les formules complètes du flux turbulent d'impuretés pour ces taux de croissance calculés des instabilités des ondes de dérive ont été dérivées. Un modèle de transport anormal qui nous permet d'étudier la dépendence du transport en fonction de la charge d'impureté a été développé. Ce modèle prend en compte les effets collisionnels entre les ions, l'impureté et les particules principales de plasma. Une telle dépendence du transport anormal en fonction de la charge de l'impureté est observée dans les expériences et il a été montré que les résultats obtenus sont en bon accord avec les observations expérimentales. Nous avons également étudié l'effet des impuretés sur le confinement de l'énergie dans les plasmas du tokamak JET. La modélisation de transport a été exécutée pour des plasmas avec injection de néon dans la périphérie du tokamak. Cette technique est utilisée afin d'extraire la chaleur par rayonnement sans endommager la paroi et pour réduire certaines instabilités (ELM). Des simulations du code RITM ont été comparées à des mesures effectuées lors d'expériences au JET. Il a été montré que l'injection de néon mène toujours à une dégradation du confinement par rapport aux décharges sans néon. Cependant, l'augmentation de la charge effective, en raison du presence du néon peut diminuer le taux de croissance d'autres instabilité (ITG) et amèliorer le confinement du coeur du plasma. Ce confinement amélioré du coeur peut alors compenser la dégradation au bord et le confinement global du plasma peut s'améliorer.
Doctorat en sciences, Spécialisation physique
info:eu-repo/semantics/nonPublished
Hoffer, Géraldine. „Fusion partielle d'un manteau métasomatisé par un liquide adakitique : approches géochimique et expérimentale de la genèse et de l'évolution des magmas de l'arrière-arc équatorien“. Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2008. http://tel.archives-ouvertes.fr/tel-00728340.
Der volle Inhalt der QuelleHackenhaar, William. „Avaliação da eficiência térmica e de fusão na soldagem MAG em diferentes geometrias de juntas“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/141208.
Der volle Inhalt der QuelleThe main aim of the present work is to study arc thermal efficiency and fusion efficiency to Gas Metal Arc Welding – GMAW, using different joint geometries. At first, the welds were performed in a continuous water flow calorimeter, followed by bead on plate and T – joint deposits. The Box-Behken design of experiments methodology was used to analyze the effect of welding parameters (arc voltage, wire feed speed and welding speed) on the efficiencies, when using short circuit metal transfer. The results of the fusion efficiency calculation were compared using different equations found in the literature. To correctly evaluate the thermal efficiency, it was necessary to analyze the influence of water flow rate and calorimeter inlet geometry. The experimental procedure consists of varying water flow rate and testing three different calorimeter inlet seal geometries: straight seal, conical diffuser seal and seal with water flux obstacle. The experiments were designed and the results evaluated based in a one-factor statistical analysis of variance, in this case the inlet calorimeter water flow. The highest average thermal efficiency is 80.5% to water flow of 4 l/min, with a low statistical error, using the conical diffuser seal inlet geometry. The inlet with straight seal model shown all the arc thermal efficiency values with slightly lower numerical values compared with conical diffuser, while the seal with flux obstacle exhibited high statistical error. Based on these results, the arc thermal efficiency was evaluated using 4 l/min water flow to the Box-Behnken Design, resulting values in the 72 to 82% range, depending on the welding parameters. The welding speed and arc voltage were the parameters that significantly affect arc thermal efficiency. The fusion efficiency results of the welds performed on the calorimeter and bead on plate were. The welds performed in T joints exhibit lowest fusion efficiency and dilution to each welding parameters combination tested. The fusion efficiency is strongly affected by the welding current.
Dalou, Célia. „Fluorine and chlorine fractionation in the sub-arc mantle : an experimental investigation“. Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00657297.
Der volle Inhalt der QuelleTkachenko, Iuliia. „Contribution à la compréhension et à la modélisation des phénomènes physiques se produisant lors d'un assemblage par procédé hybride laser-arc“. Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS012.
Der volle Inhalt der QuelleAn investigation on hybrid welding physics is presented in the current work. A literature review describes main physical processes occurring during Laser-arc combination and shows main achievements and problematics met during process analysis. Physical processes were studied during joining of very thick materials. Two configurations were used. The first configuration is welding of Superduplex steel in one pass by Laser and arc that are far apart. The second configuration is multipass welding of 18MND5 steel, where defocused Laser beam intercepts arc plasma. With a help of experiment’s design, fast video imaging, electric signals recording, determination of temperature and workpiece distortion, were explained the role of each thermal source and influence of their combination on arc behaviour, molten pool creation, metallic drop transfer evaluation and heat distribution into welded plates. The relationships between electric signals and arc geometry, bath dimensions and heat distribution have been analyzed at various time scales. Thermal analysis, presented in this work, shows that hypothesis of stationarity, which is commonly used in numerical modelling, is true only during a short welding period and for a given weld length. Macrographic analysis shows effect of input parameters variation on weld’s structure and geometry
Rousová, Michaela. „Zvýšení efektivity při svařování pecních konstrukcí“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229241.
Der volle Inhalt der QuelleGomez, Ortega Arturo. „Prototypage rapide de pièces en alliage d’aluminium : étude du dépôt de matière et d’énergie lors de la fusion à l’arc d’un fil par le procédé MIG-CMT“. Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS067/document.
Der volle Inhalt der QuelleA new additive manufacturing process for metallic parts, based on the arc welding process known as CMT (Cold Metal Transfer), is studied with the objective of building parts with the aluminium alloy Al5Si. A workbench for additive manufacturing based on the 3D printers open-source principle, on which the CMT generator was integrated, was specially developed. The CMT process allows to control the aluminium wire melting and its deposition under the form of droplets on the building surface, forming, after solidification, beads that can be superposed for the parts construction. The process parameters influence on the material transfer and heat transfer during the metal melting and deposition on the build surface, as well as on the geometric characteristics of the deposed beads, in the case of mono-layer deposits, and in the case of multi-layer walls, is studied. Many geometric defects were observed, and their apparition conditions analysed, thanks in particular to the use of a high-speed camera. The understanding of the relations between the process parameters, the melting and heat transfer mechanisms, and the beads geometry, allowed the defects correction by identifying and modifying the process parameters responsible of their apparition. Finally, an on-line control method for the process, based on the analysis of the voltage and current signals produced by the welding generator during the deposition phenomena, making possible the early detection of defects, and then the modification of the process parameters before they are amplified, has been proposed
Dubaux, Dominique. „De la nucléation aux interfaces : croissance de phases intermétalliques complexes sur substrats cristallins“. Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0235.
Der volle Inhalt der QuelleComplex metal alloys (CMA) refer to intermetallic compounds with large to giant unit cell (even "infinite" for quasicristals), presenting a sub-structure in aggregates assembled according to precise rules. CMA exhibit physical and chemical properties, in particular of the surface, which may be of interest for a certain number of laboratory and industrial applications. We will mention for example the catalytic, tribological and anticorrosive properties. To functionalize these materials, it is necessary to process them in the form of thin layers or in composites. The quality of the surfaces but also of the interfaces between these CMA and the crystal lattice of the substrate or of the matrix is then essential.In our studies, we have followed, at the nanometer scale, the formation of complex intermetallic phases, with specific surface properties, by Fe deposition on unary Al(100) and binary Al9Co2(001) substrates. The resulting systems are characterised by experimental surface techniques (low energy electron diffraction, scanning tunneling microscopy, X-ray photoemission spectroscopy). From these analyses, it follows that the phases formed are stabilized by epitaxy. This includes the metastable Al9Fe2 phase, the high temperature Al8Fe5 phase, the mixed Al9(Fe,Co)2 phase and the Al13Fe4 quasicrystal approximant. We have characterised the structures and properties of the interfaces formed between the CMA and the substrates by high-resolution transmission electron microscopy in order to obtain an atomic description of the interface. These results have been supplemented by ab initio calculations using density functional theory. We have also attempted the direct synthesis of the metastable intermetallic Al9Fe2 by arc melting and melt spinning and then characterised the phases obtained during these processes by X-ray diffraction, scanning and transmission electron microscopies
Nguyen, Minh Chien. „Modélisation et simulation multiphysique du bain de fusion en soudage à l'arc TIG“. Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4749/document.
Der volle Inhalt der QuelleIn this work, we develop a 3D physical and numerical model of the GTA (gas tungsten arc) welding process in order to predict, for given welding parameters, useful quantities for the designer of welded assembly.The model is developed in the Cast3M finite element software and takes into account the main physical phenomena acting in the workpiece and particularly in the weld pool, subject to source terms modeling the arc part of the welding process. A steady solution of this model is thought for and involves the coupling of the nonlinear thermohydaulics and electromagnetic equations together with the displacement of the deformable free surface of the weld pool.A first step in the development consisted in modeling the electromagnetic phenomena with two different numerical methods, in comparing the numerical results obtained with those of the literature. Then, in order to assess the predictive capability of the model, simulations of various welding configurations are performed : variation in the chemical composition of the material, of the welding speed, of the prescribed arc pressure and of the welding positions, which is a focus of this work, are studied. A good agreement is obtained between the results of our model and other experimental and numerical results of the literature. Eventually, a model accounting for metal filling is proposed and its results are discussed. Thus, our complete model can be seen as a solid foundation towards future totally-coupled 3D welding models including the arc and it will be included in the WPROCESS software dedicated to the numerical simulation of welding
Garguet-Duport, Bruno. „Fusion d'images et télédétection en écologie du paysage : application à l'étude structurale d'un corridor fluvial alpin“. Grenoble 1, 1994. http://www.theses.fr/1994GRE10159.
Der volle Inhalt der QuelleLe, Guen Emilie. „Etude du procédé de soudage hybride laser/MAG : Caractérisation de la géométrie et de l'hydrodynamique du bain de fusion et développement d'un modèle 3D thermique“. Phd thesis, Université de Bretagne Sud, 2010. http://tel.archives-ouvertes.fr/tel-00546986.
Der volle Inhalt der QuelleHans, Stéphane. „Modélisation des transferts couplés de chaleur, de soluté et de quantité de mouvement lors de la refusion à l'arc sous vide (VAR) : application aux alliages de titane“. Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL023N.
Der volle Inhalt der QuelleMavier, Fabrice. „Procédé de projection plasma en mode pulsé associé à une injection jet d'encre synchronisée : mise au point, processus en vol et élaboration de dépôts céramiques“. Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0065/document.
Der volle Inhalt der QuelleIn the field of thermal spray coating processes, research has led to the development of nanostructured coatings by suspension plasma spraying (SPS) and precursor solution plasma spraying (SPPS). Liquid injection are promising techniques with the potential to become industrially viable. However, a better control of plasma/material interactions is necessary. Mono-electrode DC torches indeed generate strongly fluctuating plasma that modifies the thermal and dynamic transfers to the injected droplet, resulting in an inhomogeneous treatment of the latter. This directly influences the texture and microstructure of deposits and subsequently their properties. Previous works have shown the origins of these instabilities. As an alternative to instabilities attenuations, a new approach is proposed: the reinforcement and modulation of the instabilities. The adjustment of process parameters has allowed obtaining a pulsed laminar plasma with a modulation of its properties. A low powered home-made modulated DC torch is used and operates with pure nitrogen as plasma forming gas. This device is synchronized with a Drop-On-Demand injection system to reproduce the same conditions of plasma/material interactions for each injected droplet. Solutions and suspensions are injected to make homogeneous coatings with controlled microstructure. The objectives of this work are firstly to characterize and understand plasma / droplet heat and dynamics transfers. Secondly, to highlight the influence of the synchronization and operating parameterson the coatings obtained
Banos, Julien. „Modélisation du procédé de refusion à l’arc sous vide : Échanges thermiques et défauts de solidification“. Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0117.
Der volle Inhalt der QuelleThe Vacuum Arc Remelting (VAR) process is used in the production of high-added value metals such as titanium alloys or nickel-based superalloys for the aerospace industry. The control of solidification conditions is an important industrial issue in order to process ingots of adequate chemical homogeneity and free of solidification defects. The work presented in this manuscript aims at improving the description of heat exchanges in a VAR process model (SOLAR) and at proposing a new approach for the prediction of segregated channels type solidification defects. First, the description of the heat exchanges in the model between the electrode, the ingot, the mould and the cooling circuit has been improved. These modifications were validated by comparing the numerical results with measurements from real industrial melts. An original experimental apparatus for measuring the external mould temperature adapted to industrial melts was designed. This apparatus was used during an experimental campaign on an industrial site during the remelting of a titanium alloy. The measurements obtained were compared with the numerical results from SOLAR. These two activities led to a first implementation of the side-arcing phenomenon in the model. In parallel, a multi-scale numerical approach was developed to predict the formation of segregated channels as a function of local solidification conditions. A first study on a Sn-Pb alloy was carried out and a mathematical criterion was calculated from the results. This first study shows a much lower impact of the thermal gradient on the formation of segregated channels than that generally considered in the literature
Poullain, Thomas. „Etude numérique et expérimentale de l’évaporation sous vide d’alliages métalliques : application à la refusion VAR de Zircaloy-4“. Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0189.
Der volle Inhalt der QuelleComposition and chemical segregation control is primordial when producing high value-added materials, such as zirconium alloys for nuclear industry. Vacuum processing allows production very high purity ingot, however it also presents an additional problematic concerning control and prediction of alloy elements evaporation. This PhD dissertation aims at improving prediction of volatile metallic species evaporation during vacuum elaboration, especially during Zircaloy 4 VAR (Vacuum Arc Remelting).First, the evaporation kinetics and the expansion of the metal vapour produced during vacuum melting is investigated. The study is done with a combination of volatilisation experiments using an experimental electron beam furnace and particle based numerical simulation (FPM) of vapour behaviour. Our volatilisation studies on pure metals, Ti and Zr, show the importance of collisions above the liquid on the vapour expansion and its recondensation. Determination of Fe and Sn vapour expansion during Zy4 vacuum melting combined with particle simulation, allowed us to determine thermodynamic activity coefficients values for these elements in liquid Zy4.Then, metallic vapour expansion under VAR conditions is studied, with particular interest shown to condensation flows on the different surfaces. Application of our numerical model to Zy4 shows that the vapour deposited on the mould has a very different composition compared to the alloy. Finally, the particle model is coupled to an ingot growth model and we study the influence of evaporation, condensation and crown reincorporation with regard to volatile solute segregation and depletion. This coupling also provides a first prediction of crown thickness and composition and we compare them to industrial crown samples
Revil-Baudard, Mathieu. „Modélisation et étude de la macroségrégation au cours de la refusion à l'arc sous vide : application aux alliages de zirconium“. Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0297/document.
Der volle Inhalt der QuelleVacuum Arc Remelting (VAR) is used to produce high performance alloys for the aeronautic (special steels, superalloys, titanium alloys) and nuclear (zirconium alloys) industries. As for all casting processes, the control of the chemical homogeneity and the metallurgical structure in VAR ingots is an important industrial issue. The goal of this thesis is to identify, for zirconium alloys in particular, the effects of the natural convection and the forced convection due to the electromagnetic stirring on macrosegregation. To this purpose, a numerical model has been developed. It is based on the solution of the coupled transient energy, momentum and solute transport equations, under laminar or turbulent flow conditions. The solidification modeling accounts for a full coupling between energy and solute transport in the mushy zone. The finite diffusion of solutes in both solid and liquid phases can be taken into account to describe microsegregation. In addition, chemically homogeneous Zircaloy-4 and M5® electrodes have been specially remelted in an industrial VAR furnace at the CEZUS plant in Ugine (Savoie, France). The macrosegregation of the ingots has been measured. The comparison between the experimental measurements and the simulation results showed that for an alloy with a large solidification interval (like Zircaloy-4), the solutal convection in the mushy zone could have an essential influence on the macrosegregation in the inner part of the ingot. Furthermore, the motion of equiaxed grains caused by a strong stirring seems to seriously intensify macrosegregation in the outer part of the ingot. For an alloy with a small solidification interval (like M5®), we have shown that the macrosegregation depends more specifically on the forced convection due to the type of stirring applied during the remelting
Nylander, Åsa. „Sensorfusion för ACC-System“. Thesis, Linköping University, Department of Science and Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8341.
Der volle Inhalt der QuelleGenom att fusionera (sammanföra) data från olika sensorer kan ett resultat uppnås som ger mer än de enskilda sensorerna var för sig. Här utreds vilka sensorer och sensorfusionsmetoder som kan vara aktuella att använda för Scanias adaptiva farthållare (ACC). Den adaptiva farthållaren anpassar det egna fordonets hastighet inte bara till en förinställd hastighet utan även till framförvarande fordons hastighet. Scanias ACC-system använder idag en radar för måldetektering.
Det finns ett antal algoritmer och arkitekturer som passar för sensorfusionssystem beroende på nivån hos sensordatan och användningsområdet. Minstakvadratmetoder kan användas då data ska matchas mot en fysisk modell, ofta med lågnivådata. När tillgänglig data är på den nivån att den används direkt för att fatta beslut kan sannolikhetsmetoder användas. Intelligent fusion består av kognitiva modeller som avser härma den mänskliga beslutsprocessen. Till detta passar data på hög nivå.
Två lösningar, för två olika sensoruppsättningar, har tagits fram. Båda lösningarna är uppbyggda av bayesiska nätverk. Det första nätverket fusionerar data från den befintliga radarenheten med data från en kamera som detekterar vägmarkeringar. Resultaten visar att filbyten kan upptäckas tidigare i och med fusionen. Det andra nätverket använder sig av två radarenheter, den ursprungliga samt en likadan enhet till, vilket resulterar i ett bredare synfält. Nätverket avgör vilka mål hos respektive radar som kan anses vara samma matchade mål. Informationen kan användas för att öka redundansen i systemet samt för att upptäcka mål tidigare än förut.
By fusing data from different sensors a result can be achieved that is worth more than the data from each sensor by itself. Which sensors and sensor fusion methods that could be used in Scania's adaptive cruise control system (ACC) is investigated. The ACC system adapts the vehicle's speed not only to a driver decided set speed but also to the speed of preceding vehicles. Scania's ACC system uses a radar for target detection.
There exists a number of algorithms and architectures fit for use in sensor fusion systems. Which one to use depends on the level of the data to be fused and on the field of application. Least square methods are used when matching data to a physical model, data to be used is often at a low level. When working with data at decision level, probability methods are favored. Another example is intelligent fusion, cognitive methods intending to mimic the human decision process. Suitable data is data at a high level.
Two solutions, for two different sensor sets, are proposed. Both solutions are made out of Bayesian networks. The first one fuses data from the existing radar unit with data from a camera which detects lane markings. The results show that lane changes can be detected earlier thanks to the fusion. The second network uses two radar sensors of the same kind as the first, resulting in a wider field of view. The network decides which ones of each radars targets that are the same matching targets. This information could be used to increase the redundancy of the system and to detect targets earlier.
Ulshöfer, Matthias. „Kontrollerwerb in der Fusionskontrolle : eine Untersuchung im europäischen, deutschen und US-amerikanischen Fusionskontrollrecht /“. Baden-Baden : Nomos, 2003. http://catalogue.bnf.fr/ark:/12148/cb400442433.
Der volle Inhalt der QuelleProuteau, Gaëlle. „Contribution des produits de fusion de la croûte océanique subductée au magmatisme d'arc : exemples du Sud-Est asiatique et approche expérimentale“. Brest, 1999. http://www.theses.fr/1999BRES2046.
Der volle Inhalt der QuelleMUCSI, CRISTIANO S. „Proposição de um processo alternativo à fusão via forno VAR para a consolidação de cavacos prensados de zircaloy e estudo do sistema dinâmico do arco elétrico“. reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11400.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Caillault, Bruno. „Fusion d'oxydes par induction haute-fréquence“. Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37603557f.
Der volle Inhalt der QuelleJULIO, JUNIOR OSWALDO. „Contribuicao ao estudo da fusao a arco sob atmosfera de gas inerte da esponja de zirconio“. reponame:Repositório Institucional do IPEN, 1990. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10244.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Soller, Aude Jardy Alain. „Refusion à l'arc sous vide du superalliage 718 modélisation du procédé et étude de la formation des "white spots /“. Vandoeuvre-les-Nancy : INPL, 2006. http://www.scd.inpl-nancy.fr/theses/2006_SOLLER_A.pdf.
Der volle Inhalt der QuelleSantos, Hachiley Polly de Castro. „Redução do consumo específico de energia elétrica total no processo de fusão em um forno elétrico a arco /“. Guaratinguetá, 2019. http://hdl.handle.net/11449/183324.
Der volle Inhalt der QuelleResumo: O aço é um dos materiais mais utilizados em todo o mundo, é possível ser 100% reciclado, obtendo novo aço sem perda de qualidade e quantas vezes for necessário. O setor siderúrgico é o maior consumidor de energia final destinado a indústria. Para produção do aço existem diversas alternativas possíveis. Neste trabalho é destacada a do forno elétrico a arco, a mais eficiente em termos de energia consumida e a única a qual pode-se utilizar como matéria-prima até 100% de material reciclado. Sendo o aço uma commodity, uma mercadoria básica facilmente intercambiável e utilizada como insumo para produção de outros produtos, tem seu preço regulado pelo mercado e trabalhos em eficiência energética são essenciais para a competitividade das empresas. O presente trabalho visa elaborar sugestões de métodos e tecnologias que possibilitem a redução do consumo específico de energia elétrica em kWh/t (quilowatt hora por tonelada de aço) para o processo de fusão do aço de um forno elétrico a arco, localizado na região do Vale do Paraíba. A metodologia empregada foi a pesquisa-ação, tendo um forno elétrico a arco real, disponível para estudos e captura de dados. As soluções encontradas estão desde técnicas operacionais de produção, até tecnologias em reaproveitamento de gases de exaustão, utilizados para o pré-aquecimento de sucata. Como resultado da pesquisa, obteve-se um conjunto de possibilidades tecnológicas com ganhos de até 143 kWh/t, o que representa cerca de 34% de redução no consumo es... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Steel is one of the most widely used materials worldwide, and it is possible to recycle 100% of it so as to generate new steels without quality loss and as many times as needed, however, the steel sector is the largest final energy consumer. There are several possible routes for steel production, but the Electric Arc Furnace has been selected for the present work due to being the most efficient in terms of energy consumption and it is the only one that can use up to 100% of recycled matter as raw material. As steel is a commodity, a basic goods easily interchangeable and used as input for the production of other products, its price is set by the market and energy efficiency studies are essential for the competitiveness of companies. The present work aims to elaborate suggestions of methods and technologies that allow the reduction of the specific electric energy consumption in kWh/t (kilowatt hour per ton of steel) by the steel melting process of an electric arc furnace located in the region of the Paraíba Valley. The methodology used was the action research, having an electric arc furnace, available for studies and data capture. The identified solutions range from operational production techniques to exhaust gas recovery technologies for scrap preheating. As a result, a set of technological possibilities with savings of up to 143 kWh/t have been obtained, which represents about 34% reduction in specific electric energy consumption by taking into account an average consumptio... (Complete abstract click electronic access below)
Mestre
Barbaro, Jacques. „Contribution à la fusion par confinement inertiel“. Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37602588g.
Der volle Inhalt der QuelleEl, Mir Hafid. „Comportement de l'arc électrique et fusion de l'électrode consommable dans un four de refusion VAR“. Vandoeuvre-les-Nancy, INPL, 2005. http://www.theses.fr/2005INPL040N.
Der volle Inhalt der QuelleThe present study is aimed to improve our knowledge of the electric arc in the Vacuum Arc Remelting VAR process, as weil as characterize the cathode melting stage. The first step consisted in investigating, thanks to an experimental modulus, the behaviour of the electric arc during the remelting of zirconium alloys, for various operating conditions. High speed video camera observations have put in evidence the influence of the cathode tip shape and the effect of applying an external magnetic field on the movement of the clusters of cathode spots. Besides, infrared thermography measurements show qualitatively that the electrode height thermally affected by the arc is very sm ail and depends on the melt rate. The goal of the second part of this work is the development of a numerical model to simulate the motion of clusters of spots at the tip of the cathode. Coupling this approach with the simulation of the behaviour of a plasma jet emitted by a single cluster, previously established in LSG2M, enables calculating the power distribution at the VAR ingot top as a function of process parameters (current, electrode geometry and external magnetic field). Ln a third step, a thermal model of the consumable electrode during melting has been written, assuming a 2D axisymmetrical geometry. Using the operating parameters as model inputs, it predicts in particular the melting rate value and evolution of the cathode tip shape. The model was validated through simulating the three successive remeltings of a zirconium alloy, following an industrial processing route
Valiente, Bermejo María Asunción. „Modelització del nivell de ferrita "delta" (FN) als acers inoxidables austenítics sotmesos a fusió per arc elèctric“. Doctoral thesis, Universitat de Barcelona, 2010. http://hdl.handle.net/10803/1081.
Der volle Inhalt der QuelleCr(eq)/Ni(eq) en la que es produeix la transició entre els modes de solidificació primaris [AP] i [FA]. Per això s'han preparat dues sèries de mostres d'acers inoxidables austenítics mitjançant forn de refusió amb arc elèctric, de manera que s'han mantingut els nivells d'aliatge constants (Cr(eq)+Ni(eq))=30% i (Cr(eq)+Ni(eq))=40% i s'ha anat variant la ràtio Cr(eq)/Ni(eq) entre 1.22 i 2.00 a cada sèrie.
De forma complementària s'ha validat la metodologia emprada, determinant experimentalment l'ordre de magnitud de les velocitats de refredament a les que s'ha sotmès el metall, quantificant les variacions de composició química experimentades pel material en ser refós per arc elèctric i optimitzant el procediment experimental en la preparació de mostres per arc elèctric en forn d'atmosfera inert.
Els resultats obtinguts han permès determinar la importància de les variables (Cr(eq))+Ni(eq)) i (Cr(eq)/Ni(eq)) en la microestructura dels acers inoxidables austenítics, de manera que s'ha modelitzat el nivell de ferrita "delta" en funció d'aquestes dues variables. A partir d'aquest model establert pels inoxidables austenítics fosos en les condicions marcades per l'arc elèctric, només coneixent la composició química del material es pot aconseguir predir el nivell de ferrita diferint de l'experimental entre (-1.11,+3.13) FN amb una fiabilitat del 95%. La informació obtinguda en aquest estudi sobre l'evolució microestructural de les mostres en funció de la composició química en les condicions de fusió per arc elèctric, pot ser de molta utilitat en el camp de la soldadura, donat que aporta una informació complementaria al diagrama de fases Fe-Cr-Ni.
This research showed the experimental results obtained when analysing the level of residual "delta" ferrite under electric arc cooling rate conditions. Results in the experimental determination of the Cr(eq)/Ni(eq) critical ratio at which the transition between [AF] and [FA] primary solidification modes are also depicted. With this aim, two series of austenitic stainless steel samples have been prepared using an arc electric remelting furnace, keeping the alloying level constant at (Cr(eq)+Ni(eq)=30% and (Cr(eq)+Ni(eq))=40% and increasing the Cr(eq)/Ni(eq) ratio from 1.22 up to 2.00 in each series.
Additionally, the methodology used has been validated experimentally, establishing the order of magnitude of the cooling rates followed by the metal, assessing the variations in chemical compositions experienced by the materials while being remelted by electric arc and optimizing the experimental procedure for samples preparation using arc electric remelting furnace under inert gas protection.
The results obtained have led to the importance of the variables (Cr(eq)+Ni(eq)) and (Cr(eq)/Ni(eq)) in the microstructure of austenitic stainless steels, and a model for the "delta" ferrite content has been proposed according to both variables. As a consequence of the modelling established for austenitic stainless steels, melted and solidified according to electric arc conditions, it is possible to forecast the level of "delta" ferrite within a 95% reliability between (1.11,+3.13)FN just considering the chemical composition of the alloy. The information provided in this research regarding the microstructural evolution of the samples in terms of the chemical composition under electric arc melting and cooling conditions can be helpful in the welding industry, as it provides complementary information to the Fe-Cr-Ni phase diagram.
KEY WORDS: Delta-ferrite, Austenitic stainless Steels, Electric Arc, Welding, Materials Technology
Fernandes, Marcos Gonzales. „Obtenção de fios em ligas cobre-magnésio para utilização em linhas de transmissão de energia elétrica“. Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-31102011-090400/.
Der volle Inhalt der QuelleThe aim of this work was to obtain copper wires in three different chemical compositions starting from electrolytic copper and magnesium. The mains steps were evaluated, starting from the melting of small eutectic cooper-magnesium specimens in an electric arc furnace, followed by further dilution of this buttons in a resistive furnace and casting it in a copper mould. The as cast billets were homogenized in a resistive furnace at 910 ºC for 2 h. The billets were mechanically cold worked by swaging and a final drawing step to attain a round shape and a reasonable surface quality. The cast ingots chemical analysis indicated that the processing route showed to be adequate, in laboratory scale, to obtain wires with cross sectional area of 4 mm2 and 10 m in length. The wires in both conditions as cold worked and after a recovering heat treatment at 510 ºC for 1 h, were mechanically characterized by tensile testing and hardness. The wires had also the electric conductivity assessed in the recovered heat-treated state and the results were compared to the literature data. The obtained material showed to be adequate to be used as electric conductor. The yield strain and ultimate tensile strength were improved with the increasing amount of Mg in the alloy, 11 % and 24 %, respectively, while the electric conductivity decreased to 60 % IACS (International Annealed Copper Standard).
Pérez, del Río Elena [Verfasser], und Heinz [Akademischer Betreuer] Clement. „ABC Effect and d* Resonance in Double-Pionic Fusion to 3He / Elena Pérez del Río ; Betreuer: Heinz Clement“. Tübingen : Universitätsbibliothek Tübingen, 2014. http://d-nb.info/1162971304/34.
Der volle Inhalt der QuelleBelkhouche, Mohammed Yassine. „Multi-perspective, Multi-modal Image Registration and Fusion“. Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc149562/.
Der volle Inhalt der QuelleGerpott, Torsten J. „Integrationsgestaltung und Erfolg von Unternehmensakquisitionen /“. Stuttgart : Schäffer-Poeschel, 1993. http://catalogue.bnf.fr/ark:/12148/cb37438078h.
Der volle Inhalt der QuelleRodegra, Jürgen. „Zum Problem aufsichtsfreier Verwaltung durch das Bundeskartellamt : untersucht am Beispiel des Fusionskontrollverfahrens /“. Frankfurt am Main ; Berlin ; Bern [etc.] : P. Lang, 1992. http://catalogue.bnf.fr/ark:/12148/cb37396380g.
Der volle Inhalt der QuelleKloe, Joost de. „Pellet-plasma interaction in a tokamak /“. [S.l. : s.n], 2000. http://catalogue.bnf.fr/ark:/12148/cb37725261x.
Der volle Inhalt der QuelleHouzelle, Stéphane. „Extraction automatique d'objets cartographiques par fusion d'informations extraites d'images satellites /“. Paris : École nationale supérieure des télécommunications, 1993. http://catalogue.bnf.fr/ark:/12148/cb355798989.
Der volle Inhalt der QuelleBrunet, Pierre. „Fusion en creuset froid et pulvérisation de carbure de tungstène“. Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37603504v.
Der volle Inhalt der QuellePricking, Annette [Verfasser], und Heinz [Akademischer Betreuer] Clement. „Double Pionic Fusion to 4He - Kinematically Complete Measurements over the Energy Region of the ABC Effect / Annette Pricking ; Betreuer: Heinz Clement“. Tübingen : Universitätsbibliothek Tübingen, 2011. http://d-nb.info/1162969946/34.
Der volle Inhalt der QuelleBAULY, JULIO C. „Caracterizacao microestrutural e propriedades de juntas dissimilares entre acos inoxidaveis fabricados por processos de fusao“. reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10832.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Janez, Fabrice. „Fusion of information sources defined on different non-exhaustive reference sets /“. Paris : ONERA, 1998. http://catalogue.bnf.fr/ark:/12148/cb367050865.
Der volle Inhalt der QuelleKunduri, Sudha Vadrevu. „Traitement et fusion de données multi-sources : restitution du cadastre romain /“. Paris : École nationale supérieure des télécommunications, 2000. http://catalogue.bnf.fr/ark:/12148/cb376487033.
Der volle Inhalt der QuelleNouicer, Rachid. „Processus de Fusion-Fission et Spectroscopie Gamma des Produits Binaires dans les Collisions entre Ions Lourds L'egers (40 < ANC < 60)“. Phd thesis, Université de Strasbourg, 1997. http://tel.archives-ouvertes.fr/tel-00805800.
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