Thermo-mechanical stress of bonded wires used in high power modules with alternating and direct current modes

Today, power electronic reliability is a main subject of interest for many companies and laboratories. The main process leading to the IGBT failure is the cycling thermal stress. Indeed the current flow induce local heating and then mechanical stress. This paper deals with electro thermal stress under steady and transient current states. The main objective is to test bonded wires with active current cycle. Consequently, the thermo mechanical stress is obtained. A numerical 3D finite element model is presented and some experimental results are given. Indeed an infrared system monitors the temperature dispatching from an experimental test bench under active current cycle. The overall study is a first step before a global simulation (electrical thermal-mechanical) in order to optimize some geometric parameters of the packaging

Mechanical stress induced by electromagnetic forces on wire bonds of high power modules

This paper concerns the analytical determination and experimental characterization of electromagnetic forces exerted on high power IGBT wire bonds

The effect of the solar wall heating on the flow structure within the cross-ventilation of isolated building

In this paper a comprehensive study is conducted on the heat transfer between building and the atmosphere within a cross ventilation situation, this situation is characterized by a transverse flow between the two parallel windows of an isolated building.  The study is divided into two parts, in the first part, the effect of the walls, solar heating during the day (windward between sunrise and noon, the roof at the moon and leeward between noon and sunset) on the air temperature distribution and air velocity inside and outside an isolated building is studied when a numerical simulation is conducted in an atmospheric micro scale. For the second part, the study is focused on the effect of temperature change of the building floor, by an external heating source such as a recessed serpentine, on cooling or heating the air but in this case only inside the building by numerical simulation. The numerical results are validated using experimental measurements (velocity profiles and turbulent kinetic energy) of Y. Tominaga realized at Niigata Institute of Technology in Japan, these measurements provide a very useful database for validation of numerical models of computational fluid dynamics (CFD). Compared to those wind tunnel experimental measurements, the numerical results of the cross-ventilation show a good agreement. The detailed results analysis shows that the differential heating of all building surfaces can greatly influence the capacity of the flow to transport and exchange heat

The effect of the solar wall heating on the flow structure within the cross-ventilation of isolated building

In this paper a comprehensive study is conducted on the heat transfer between building and the atmosphere within a cross ventilation situation, this situation is characterized by a transverse flow between the two parallel windows of an isolated building.  The study is divided into two parts, in the first part, the effect of the walls, solar heating during the day (windward between sunrise and noon, the roof at the moon and leeward between noon and sunset) on the air temperature distribution and air velocity inside and outside an isolated building is studied when a numerical simulation is conducted in an atmospheric micro scale. For the second part, the study is focused on the effect of temperature change of the building floor, by an external heating source such as a recessed serpentine, on cooling or heating the air but in this case only inside the building by numerical simulation. The numerical results are validated using experimental measurements (velocity profiles and turbulent kinetic energy) of Y. Tominaga realized at Niigata Institute of Technology in Japan, these measurements provide a very useful database for validation of numerical models of computational fluid dynamics (CFD). Compared to those wind tunnel experimental measurements, the numerical results of the cross-ventilation show a good agreement. The detailed results analysis shows that the differential heating of all building surfaces can greatly influence the capacity of the flow to transport and exchange heat

Synthesis, characterization and study of copolymer/surfactant mixture in aqueous solution by conductivity and viscosity techniques

The copolymer CPAV was synthesized by radical copolymerization. The acid chloride was added to this copolymer to produce the CPAVCl. The conductivity and viscosity measurements were used to study the interaction of CPAVCl with an anionic surfactant-sodium dodecyl sulfate (SDS) in aqueous solutions of different concentrations at 25°C. The result shows that the values of conductivity and viscosity system were influenced by the surfactant concentration, polymer concentration and salinity. It is observed that the surfactants induced cooperative binding with the polyelectrolyte at critical aggregation concentration (CAC). The CAC values are considerably lower than the corresponding critical micelle concentration (CMC) of the surfactant. Thus, the saturation of the polyelectrolyte by the surfactant molecules occurs at the concentration of saturation (X2) which is greater than the (CMC).  

Les retraductions françaises d'Al Moqqadima d'Ibn Khaldoun : étude paratextuelle des retraductions de Vincent-Mansour Monteil (1967) et d’Abdesselam Cheddadi (2002)

Ce mémoire porte sur les retraductions françaises du XXe siècle d’Al Moqaddima (Les Prolégomènes) (1377) d’Ibn Khaldoun, un traité historique et philosophique du XIVe siècle. La première traduction française, Les Prolégomènes, est réalisée par De Slane entre 1840 et 1863. Elle est suivie de deux retraductions, à savoir Discours sur l’histoire universelle (1967- 1968) réalisée par Vincent-Mansour Monteil, et Le Livre des Exemples I : Autobiographie, La Muqaddima (2002) réalisée par Abdesselam Cheddadi. L’objet de ce mémoire est de mener une analyse contextuelle, paratextuelle et discursive de ces deux retraductions de l’œuvre monumentale d’Ibn Khaldoun, afin de dégager les principaux facteurs déterminant, dans chaque cas, le choix de retraduire. Notre approche théorique s’inscrit dans le contexte récent de remise en cause de ladite « hypothèse de la retraduction » d’Antoine Berman, qui privilégie une analyse textuelle de l’œuvre (re)traduite en négligeant quelque peu l’analyse contextuelle éclairant les conditions de production des retraductions, et en limitant le positionnement du traducteur à sa relation envers la « vérité » du texte source. Ainsi, en retraçant l’histoire des différentes éditions des Prolégomènes au XXe siècle, en exposant le contexte qui entoure les retraductions, et en nous nous attachant aux stratégies discursives déployées par les traducteurs en marge de ces dernières, nous tenons compte des réflexions récentes sur les « causalités multiples » du phénomène de la retraduction, tout en montrant comment la subjectivité du traducteur, ses décisions et ses motivations sont reliées à tous les éléments extratextuels ou contextuels mis en valeur par les théoriciens. Nous montrons par notre analyse que les deux retraductions au corpus sont motivées par des facteurs internes au texte (tels que l’authenticité de leur original, une meilleure connaissance du texte, de la langue et de la culture source, la nécessité de corriger des erreurs dans les traductions antérieures), mais aussi par de nouveaux éléments externes au texte (tels que le changement de normes sociales, littéraires et traductionnelles, l’émergence de nouvelles interprétations du texte, le positionnement idéologique du retraducteur, sa volonté de s’imposer comme une autorité, etc.). La retraduction s’avère donc un phénomène complexe motivé par une combinaison de facteurs, à la fois internes (textuels), externes (contextuels) et personnels, propres au (re)traducteur.This thesis studies the XXth-century French retranslations of Ibn Khaldun’s XVIth- century historical and philosophical treatise Al Moqaddima (or Prolegomena, 1377). The first French translation as Les Prolégomènes was written by De Slane between 1840 and 1863. It was followed by two XXth-century retranslations, respectively entitled Discours sur l’histoire universelle (1967-1968) by Vincent-Mansour Monteil, and Le Livre des Exemples I : Autobiographie, La Muqaddima (2002) by Abdesselam Cheddadi. This thesis explores the contexts, paratexts, and discursive strategies surrounding each retranslation of Khaldun’s monumental treatise, in order to clarify the major factors that determine, in each case, the translator’s decision to retranslate. Our theoretical approach stems from recent debates around Antoine Berman’s “retranslation hypothesis”, which focuses on a textual analysis of retranslations, and tends to downplay the importance of the context surrounding the production of retranslations, and limits the translator’s positioning to his/her relationship to the “truth” of the original. By documenting the history of XXth-century editions of Khaldun’s Prolegomena, by establishing the context surrounding each retranslation, and by analyzing the discursive strategies deployed by each retranslator in the margins of his work, our study takes into account recent theories of “plural causality” in retranslation; we also highlight the ways in which the translators’ subjectivity, their choices and motivations are deeply connected with the extra-textual, or contextual elements emphasized by such theories. Our analysis shows the two translations under study to be motivated by internal, textual factors (such as: more authentic original manuscripts, better textual criticism and understanding of the source language and culture, the necessity to correct errors in the previous translations, etc.), but also extra-textual, or contextual factors (changing social, literary and translation norms, new interpretations of the original, the translator’s ideological position and need to establish his authority, etc.). In the end, retranslation emerges as a complex phenomenon deriving from a variety of causes, at once internal (textual), external (contextual), and personal, that is, due to the translator’s own agency

Contribution à la simulation électro-thermomécanique numérique 3d : appliquée à l'étude de la fiabilité des interrupteurs à semiconducteurs packages, utilisés en traction ferroviaire

La tendance actuelle dans le domaine du transport ferroviaire est d’intégrer des modules de puissance de plus en plus puissants dans des volumes de plus en plus réduits. Cela pose des problèmes, notamment en termes de fiabilité, car lors de leurs cycles de fonctionnement, les interrupteurs à semi-conducteurs et leur environnement immédiat sont soumis à des contraintes électro-thermo-mécaniques plus sévères. Cela peut entraine leur destruction et donc la défaillance de la fonction de conversion d'énergie. L’objectif principal de cette thèse est de décrire des modèles et des outils de simulation multi-physiques afin de caractériser ces contraintes. Nous avons choisi comme cas d’étude les fils de connexion dits «wire bonding». Ces fils sont, en effet, considérés comme l’un des points faibles en ce qui concerne la durée de vie des modules de puissance, utilisés dans les systèmes embarqués notamment dans le ferroviaire. Dans ce contexte multi-physique, nous avons développé des modèles, numériques, éléments finis, analytiques, 3D ou 1D, afin de déterminer les contraintes thermomécaniques lors du passage du courant dans ces fils. A travers les modèles décrits et les résultats de simulation présentés, nous caractérisons le comportement des fils d’un point de vue électrique, thermique, magnétique ou mécanique. Plus précisément les interactions électromagnétiques, électrothermiques, électromécaniques ou thermomécaniques entre modèles et entre outils de simulation sont discutées. Les résultats sont confrontés aux mesures thermiques et de déplacement. Ces dernières sont réalisées par le biais de prototypes expérimentaux. Le mode de sollicitation utilisé est dit actif. Un régime de courant, continu ou alternatif, est appliqué au système. La réponse thermique et mécanique du système est alors obtenue. Les conclusions de cette étude permettent d’une part de mieux caractériser le comportement électro thermomécanique des fils de bonding et de mieux comprendre l’origine des modes de défaillance de cette technologie d’interconnexion. D’autre part, une démarche d’utilisation des modèles et outils logiciels multi physiques pour une simulation électro thermomécanique est présentée. ABSTRACT : The trend in the field of railway transport is to integrate increasingly powerful power modules in smaller volumes. This is problematic, especially in terms of reliability: during their cycles of operation, the semiconductor switches and their immediate environment are subject to tougher electro-thermo-mechanical stresses. This can lead to their destruction and then, to the failure of the energy conversion function. The main goal of this work is to describe the models and multi-physics simulation tools to characterize these stresses. We chose as a case study the connection wire called “wire bonding”. These wires are, indeed, considered one of the weaknesses of the life time of the power module used in embedded systems, particularly in railway applications. In this multi-physics context, we have developed numerical, finite elements, analytical, 3D or 1D models to determine the thermo-mechanical stresses during the current flow through the wires. Thanks to the models described and the simulation results presented, we characterize the behavior of the wire for an electrical, thermal, magnetic or mechanical point of view. More precisely, the electro-magnetic, electro-thermal, electro-mechanical or thermo-mechanical interactions between models and between simulation tools are discussed. The results are compared to thermal and displacement measurements. They are realized thanks to experimental prototypes. The type of solicitation is called active. A system of direct or alternating current is applied to the system. The thermal and mechanical response of the system is obtained. The conclusions of this study allow, on the one hand, characterizing the electro thermo-mechanical behavior of wires bonding and understanding the origin of the failure modes of this technology. On the other hand, a way of using models and multi-physics software tools for an electro thermo-mechanical simulation is presented

Structure of the out- flows behind buildings and Influence of the geometry of the streets on the out-flows

This paper intends to study the latest results from the research methods available with special intentions given to the architectural effects of the street valley and wind speed. Extensive research has been carried out through several research approaches to understand the effect of wind flow formation in the streets and the current wind condition on the structure of the wind current. The main goal of this paper is to study the structure of out- flows of buildings and the effect of street engineering on external flows. The numerical modeling is to simulate the effect of the wind flow and the layer limit on different building structures using the ANSYS Fluent package. The program was based on the K-ε model to incorporate the potential of differential equations forming the mathematical model. Three cases were considered; the first case is the height-to-width ratio of the valley (h/w), the second is the width of the dome (b3/b) and the third case the ratio of the height of the valley (h3/h) to see the effect of street valley engineering and wind speed effect

LA RETRADUCTION CRITIQUE ET SA CONTRIBUTION À L’AMÉLIORATION DE LA QUALITÉ DES TRADUCTIONS, EXEMPLE DES RETRADUCTIONS D’AL MUQADDIMA D’IBN KHALDOUN

Le présent travail porte sur les deux retraductions françaises d’Al Muqaddima (1377) d’Ibn Khaldoun, auteur d’une riche théorie de l’histoire, de la politique, de la société et de la civilisation humaine. La première traduction (1863) est celle du baron de Slane, élève de l’orientaliste célèbre Silvestre de Sacy. Cette version a suscité de nombreuses critiques qui ont pavé la voie à deux nouvelles versions se présentant comme meilleures que la précédente. Il s'agit de la retraduction (1967-1968) de Vincent Monteil, qui vise à corriger la première traduction, et de celle d’Abdassalam Cheddadi parue en 2002. Ce travail consiste à mener une analyse comparative des contextes socioculturels, politiques, historiques et personnels de ces deux retraductions, pour dégager les facteurs et les critiques qui les conditionnent. Or, ces critiques sont-elles objectives et constructives et surtout efficaces pour l’amélioration qualitative de la traduction d’Al Muqaddima