Given a political context in which energy and environmental stakes have become increasingly dominant, road engineering practices have favoured saving energy and protecting the environment. Among these practices, the use of cold mixes treated with bitumen emulsion has proven to be a suitable technique. Cold mix design however, as well as the design of pavements including cold mix asphalt layers, is highly empirical and based on local skills. From prior experience, the transposition of established local rules from one site to another and their application to medium or heavy traffic pavements are not simple steps and tend to limit the development of this environmentally-friendly pavement technique. The first step in designing a pavement consists of knowing the stress-strain relationship of its constitutive materials in order to determine the stresses and strains generated by heavy lorry traffic. During a second step, these values must be compared with the mechanical durability of materials by reliance on damage tests comprising large numbers of load cycles. In the case of CMA, no mechanical behaviour law has been established to take into account both the fresh and cured states. This work aims to improve the knowledge acquired on this material. For this, an evolutiv model for the cold mix asphalt with bitumen emulsion incorporating the evolution of the material from its fresh state to its cured state has been developed. In addition, a new characterization test was developed and put in place to monitor the evolution of the reversible mechanical performance of the material. The results obtained from the test campaigns helped to calibrate the model and show the relevance of the model. ; Dans un contexte politique où les enjeux énergétiques et environnementaux sont de plus en plus importants, il faut favoriser les techniques économes en énergie et plus respectueuse de l'environnement. Parmi ces pratiques, l'utilisation d'enrobés à l'émulsion de bitume s'est révélée être prometteuse. La fabrication et la conception d'une ...
Given a political context in which energy and environmental stakes have become increasingly dominant, road engineering practices have favoured saving energy and protecting the environment. Among these practices, the use of cold mixes treated with bitumen emulsion has proven to be a suitable technique. Cold mix design however, as well as the design of pavements including cold mix asphalt layers, is highly empirical and based on local skills. From prior experience, the transposition of established local rules from one site to another and their application to medium or heavy traffic pavements are not simple steps and tend to limit the development of this environmentally-friendly pavement technique. The first step in designing a pavement consists of knowing the stress-strain relationship of its constitutive materials in order to determine the stresses and strains generated by heavy lorry traffic. During a second step, these values must be compared with the mechanical durability of materials by reliance on damage tests comprising large numbers of load cycles. In the case of CMA, no mechanical behaviour law has been established to take into account both the fresh and cured states. This work aims to improve the knowledge acquired on this material. For this, an evolutiv model for the cold mix asphalt with bitumen emulsion incorporating the evolution of the material from its fresh state to its cured state has been developed. In addition, a new characterization test was developed and put in place to monitor the evolution of the reversible mechanical performance of the material. The results obtained from the test campaigns helped to calibrate the model and show the relevance of the model. ; Dans un contexte politique où les enjeux énergétiques et environnementaux sont de plus en plus importants, il faut favoriser les techniques économes en énergie et plus respectueuse de l'environnement. Parmi ces pratiques, l'utilisation d'enrobés à l'émulsion de bitume s'est révélée être prometteuse. La fabrication et la conception d'une chaussée comprenant une couche d'enrobé à l'émulsion sont très empiriques et reposent sur des compétences locales qui tendent à en limiter le développement. La première étape pour concevoir une chaussée consiste à connaître le comportement mécanique réversible engendrées par de lourd trafic de chaque matériau qui la compose. Lors d'une deuxième étape, ces valeurs doivent être comparées aux critères de durabilité mécanique des matériaux. Dans le cas de l'enrobé à l'émulsion, aucune loi de comportement mécanique n'a été établie pour tenir compte à la fois de son états frais et durcis. Ce travail de thèse vise donc à pallier à ce manque et à améliorer les connaissances acquises sur ce matériau. Pour cela, un modèle évolutif pour l'enrobé à l'émulsion intégrant l'évolution du matériau de son état frais à l'état durci a été développé. De plus, un nouvel essai de caractérisation a été développé et mis en place pour permettre de suivre l'évolution des performances mécaniques réversibles du matériau. Les résultats obtenus à partir des différentes campagnes d'essais ont permis de caler le modèle et de montrer la pertinence du modèle.
In Switzerland and elsewhere, many psychological support hotlines were set up during the acute phase of the COVID-19 pandemic. Specialists in psychological first aid, in charge of developing and managing these hotlines, had to face an unknown situation, very different from the disasters for which they prepare themselves. Since the pandemic and the associated physical distancing were a potential threat to social cohesion, one could make the hypothesis that, by setting up hotlines, these professionals sought to reintroduce a form of proximity and to care for and cultivate the social connections among people. The pressure, feelings of emergency, anxious anticipation and expectation of the political authorities and the population may have favoured the development of these structures. Other factors certainly also played a role, such as the need to be useful and to exist as professional, or the need to act in order to reduce anxiety related to the pandemic. Altogether, these hotlines were little used, and their usefulness may be questioned. Similar phenomena have been observed - especially in the sanitary domain - with a multiplication of new offers, not always adjusted to specific identified needs, while health care services were on the same time under-used. Our observations plead against emergency responses in crisis situations and for reflecting on the measures to be put in place rather than to "act" them.
The Dassault Aviation Group designs and builds a wide range of aircraft models each year, for both private and military use. Some structural parts of the aircraft, in the form of reinforced stiffener panels machined directly into the bulk of Al2024T351 thick plates are studied. As part of the shaping process, these elements must be cold formed to give their final curvature. This process severely plastified some regions of the structure. In addition, these zones are likely to constitute sites of initiation and propagation of fatigue cracks.This study aims to analyze the interactions between the plastic phenomena induced by cold forming and the propagation of a fatigue crack during fatigue service loading. This thesis is conducted according to the following approach:An instrumented cold forming test has been performed on two self-stiffening technological specimens. From an experimental base of tensile tests, a model of anisotropic plastic behavior of the plate was proposed allowing the development of a cold forming structure simulation and an analysis of the residual state of the material following the process. Using all the results about residual plastic state, a compression and traction test on large test pieces has been performed (54 mm diameter slugs and flat tensile test pieces of 75x55 mm section) whose purpose is to produce a homogeneous volume of pre-deformed material in compression and traction (+/-10 % of plasticity) .A large campaign of fatigue tests has been realized on oligocyclic specimens and specimens of propagation (Compact Tension) extracted from the volumes of original and pre-deformed material allowing the characterization of the effects of the pre-deformation on the fatigue properties. A modified Forman propagation model has been identified from the velocity curves.Finally, self-stiffened structures formed have been subjected to a cyclic loading and the fatigue initiation and propagation behavior has been observed experimentally. A simulation of the fatigue loading of the structure after ...
The Dassault Aviation Group designs and builds a wide range of aircraft models each year, for both private and military use. Some structural parts of the aircraft, in the form of reinforced stiffener panels machined directly into the bulk of Al2024T351 thick plates are studied. As part of the shaping process, these elements must be cold formed to give their final curvature. This process severely plastified some regions of the structure. In addition, these zones are likely to constitute sites of initiation and propagation of fatigue cracks.This study aims to analyze the interactions between the plastic phenomena induced by cold forming and the propagation of a fatigue crack during fatigue service loading. This thesis is conducted according to the following approach:An instrumented cold forming test has been performed on two self-stiffening technological specimens. From an experimental base of tensile tests, a model of anisotropic plastic behavior of the plate was proposed allowing the development of a cold forming structure simulation and an analysis of the residual state of the material following the process. Using all the results about residual plastic state, a compression and traction test on large test pieces has been performed (54 mm diameter slugs and flat tensile test pieces of 75x55 mm section) whose purpose is to produce a homogeneous volume of pre-deformed material in compression and traction (+/-10 % of plasticity) .A large campaign of fatigue tests has been realized on oligocyclic specimens and specimens of propagation (Compact Tension) extracted from the volumes of original and pre-deformed material allowing the characterization of the effects of the pre-deformation on the fatigue properties. A modified Forman propagation model has been identified from the velocity curves.Finally, self-stiffened structures formed have been subjected to a cyclic loading and the fatigue initiation and propagation behavior has been observed experimentally. A simulation of the fatigue loading of the structure after forming has been proposed. The Z-crack module of the Z-set finite element code associated with the propagation model allowed to simulate the propagation of a fatigue crack within the structure. ; Le groupe Dassault Aviation conçoit et construit chaque année un large choix de modèles d'avions, à la fois à usage privé comme à usage militaire. Nous nous intéressons ici à certaines pièces structurelles de l'avion, se présentant sous la forme de panneaux renforcés de raidisseurs usinés directement dans la masse de tôles épaisses en alliage Al2024T351. Dans le cadre du processus de mise en forme, ces éléments doivent être formées à froid afin de leur donner une courbure définitive. Ce procédé a pour conséquence de pré-déformer sévèrement certaines régions de la structure. De plus, ces zones sont susceptibles de constituer des sites d'amorçage et de propagation de fissures de fatigue.Cette étude vise à analyser les interactions entre les phénomènes plastiques induits par le formage à froid et la propagation d'une fissure de fatigue lors du chargement en fatigue de la structure. Cette thèse se déroule selon la démarche suivante:Un essai de formage à froid instrumenté a été réalisé sur deux éprouvettes technologiques auto-raidies. A partir, d'une base expérimentale d'essais de traction un modèle de comportement plastique anisotrope de la tôle a été proposé permettant l'élaboration d'une simulation du formage des deux structures ainsi que l'analyse fine de l'état résiduel du matériau suite au procédé. Après connaissance de l'état plastique résiduel, un protocole d'essais de compression et de traction sur éprouvettes grandes dimensions a été mené (des lopins de diamètre 54 mm et des éprouvettes de traction plate de section 75x55 mm) dont le but est de produire un volume homogène de matériau pré-déformé en compression et en traction (jusqu'à +/-10 %).A partir des volumes de matériaux d'origine et pré-déformés, une large campagne d'essais de fatigue a été réalisée sur éprouvettes oligocycliques et éprouvettes de propagation (Compact Tension) permettant en autres la caractérisation des effets de la pré-déformation sur les propriétés en fatigue. Un modèle de propagation de Forman modifié a pu être identifié à partir des courbes de vitesse.Enfin, les structures auto-raidies formées ont été soumises à un chargement cyclique et le comportement à l'amorçage et en propagation a pu être observé expérimentalement. Une simulation du chargement en fatigue de la structure après formage a été proposée. Le module Z-crack du code éléments finis Z-set associé au modèle de propagation à permis de simuler la propagation d'une fissure de fatigue au sein de la structure.Une conclusion sur la contributions des contraintes, de l'angle de formage et de la plasticité sur le trajet et la vitesse de propagation a pu être apportée numériquement et confrontée aux résultats des essais.
At the department of military application at cea, flash radiography is being used to image high velocity matter (few km/s), with high density. For this purpose, X-rays need to have an energy around 10MeV, to be short (60ns) and produce a dose of several hundreds of rad. To generate this kind of X-rays, an intense relativistic electron beam (typically 20MeV, a few kA during 60ns) is focused on a conversion target. During the beam/target interaction, a certain amount of the beam energy is converted into heat. Because the energy deposition is very abrupt, we observe temperature and pressure of the order of 1eV and 1Mbar. Under such extreme conditions, matter is vaporised and a plasma plume expand around the conversion target. In the context of prospective studies on a multi-pulse flash radiographic chain, our goal is to study the influence a this plasma plume on the quality of the successive X-ray pulses. To do so we want to design an experiment where we propagate a flash radiographic electron beam in a plasma. First, jointly with a bibliographic study, we made calculations using the envelop equation, modified to take into account the influence of the plasma. The key parameter in beam/plasma interaction is the ratio of their respective electronic densities. Consequently to this preliminary study, we concluded that for the design of our experiment, we needed plasmas with electronic densities between 10^10 cm^(-3) and 10^12 cm^(-3).For this purpose, we took interest in glow discharges and design a test bench to characterize them with different type of diagnostics. We performed measurements with a langmuir probe, a radiofrequency interferometer and a new diagnostic based on capacitive coupling with the plasma and we came to the conclusion that the maximum electronic density in glow discharges was of the order of 10^10 cm^(-3). Although this does not cover the whole range of electronic density, we designed a device capable of generating a glow discharge and that we could clip on the beam pipe of an accelerator. We ...
At the department of military application at cea, flash radiography is being used to image high velocity matter (few km/s), with high density. For this purpose, X-rays need to have an energy around 10MeV, to be short (60ns) and produce a dose of several hundreds of rad. To generate this kind of X-rays, an intense relativistic electron beam (typically 20MeV, a few kA during 60ns) is focused on a conversion target. During the beam/target interaction, a certain amount of the beam energy is converted into heat. Because the energy deposition is very abrupt, we observe temperature and pressure of the order of 1eV and 1Mbar. Under such extreme conditions, matter is vaporised and a plasma plume expand around the conversion target. In the context of prospective studies on a multi-pulse flash radiographic chain, our goal is to study the influence a this plasma plume on the quality of the successive X-ray pulses. To do so we want to design an experiment where we propagate a flash radiographic electron beam in a plasma. First, jointly with a bibliographic study, we made calculations using the envelop equation, modified to take into account the influence of the plasma. The key parameter in beam/plasma interaction is the ratio of their respective electronic densities. Consequently to this preliminary study, we concluded that for the design of our experiment, we needed plasmas with electronic densities between 10^10 cm^(-3) and 10^12 cm^(-3).For this purpose, we took interest in glow discharges and design a test bench to characterize them with different type of diagnostics. We performed measurements with a langmuir probe, a radiofrequency interferometer and a new diagnostic based on capacitive coupling with the plasma and we came to the conclusion that the maximum electronic density in glow discharges was of the order of 10^10 cm^(-3). Although this does not cover the whole range of electronic density, we designed a device capable of generating a glow discharge and that we could clip on the beam pipe of an accelerator. We called this device the plasma cell. In parallel, in order to be able to sweep the whole range of electronic densities, we develop an inductive heating system for the glow discharges. Interferometric measurements shows that this system allows us to reach electronic densities of the order of 10^13 cm^(-3) even though some work is required to improve its reliability before we can use it on the plasma cell.We tested the first version of the plasma cell on the FEVAIR facility at CEA-CESTA (4MeV, 2kA, 60ns). During this experimental campaign, most of the characteristics of the plasma cell were successfully tested, especially one of the most critical one : the plasma/vacuum interface. We achieved propagation of the FEVAIR beam through the plasma cell and measured the beam net current at different axial positions, as well as the beam profil at its exit. First, we observe that gas pressure was acting on the beam from a few 10^(-2) mbar, which is the minimu pressure at which we are able to generate a glow discharge. Besides, this effect is predominant on the effect of the glow discharge. In addition to that, we saw that peripheral electrons were hiting the cell, causing an electrical charge and influencing the beam propagation.This obervations have inspired some improvements on the plasma cell : its evolution will be shorter and equiped with an inductive heating system based on the one we develop during this thesis. On top of that, this experimental campaign emphasize the importance of a detailled description of the beam and its interaction with the gas in the cell, in this kind of regime. ; Le CEA-DAM utilise la radiographie éclair pour sonder des matériaux en mouvement très rapide (quelques kilomètres par seconde), dont la densité est extrêmement élevée. Pour obtenir une image de radiographie dans ces conditions, le rayonnement X doit être énergétique (autour d'une dizaine de MeV), bref (60ns) et capable de délivrer une dose de plusieurs centaines de rad. Une des voies pour générer un tel rayonnement est de focaliser un faisceau d'électrons relativistes et de fort courant (typiquement 20MeV, quelques kA pendant 60ns) sur une cible dite de conversion. Lors de l'interaction faisceau/cible, une partie de l'énergie du faisceau est transmise à la cible sous forme de chaleur. Ce dépôt d'énergie soudain engendre des températures de l'ordre de l'eV et des pressions de l'ordre du Mbar. Dans ces conditions la matière est vaporisée et un plasma se forme, en détente hydrodynamique autour de la cible de conversion. Dans le cadre d'études prospectives sur une machine de radiographie éclair multi-temps, nous souhaitons étudier l'influence d'un tel plasma sur la qualité des impulsions de rayons X successives (notamment la dose et la taille de la source). Notre objectif est donc de mettre au point une expérience de propagation d'un faisceau de radiographie éclair dans un plasma.Dans un premier temps, conjointement à une étude bibliographique, nous avons effectué des calculs à partir de l'équation d'enveloppe d'un faisceau modifiée pour modéliser l'influence d'un plasma. Le paramètre clé influençant la propagation d'un faisceau d'électrons dans un plasma est le rapport entre leur densité électronique respective. Ainsi, d'après cette étude préliminaire, nous avons déduit qu'il était intéressant d'explorer la propagation des faisceaux de radiographie éclair dans des plasmas dont la densité électronique était comprise entre 10^10 cm^(-3) et 10^12 cm^(-3).Pour cette application, nous nous sommes intéressés aux décharges luminescentes : nous avons mis au point un banc de test afin de les caractériser au moyen de différents diagnostics. Après des mesures par sonde de Langmuir, interférométrie radiofréquence et un nouveau diagnostic basé sur un couplage capacitif avec le plasma, nous en avons déduit que la densité électronique maximale des décharges luminescentes était de l'ordre de 10^10 cm^(-3). Bien que cela ne couvre pas l'ensemble du domaine d'intérêt, nous avons conçu un dispositif (« cellule plasma ») capable de générer une décharge luminescente et adaptable sur l'axe d'un faisceau afin de propager ce dernier à l'intérieur. En parallèle, afin de balayer l'ensemble de la plage de densité électronique nous intéressant, nous avons mis au point un système de chauffage inductif de nos décharges afin d'augmenter leur densité. Bien que des mesures par interférométrie montrent que le chauffage nous permet d'atteindre des densités électroniques de l'ordre de 10^13 cm^(-3), un travail de fiabilisation est nécessaire afin de mieux maîtriser le procédé avant de le porter sur faisceau [.]
National audience for centuries, the Caribbean basin has experienced divergent rivalries and interests between the major European powers. However, since the end of the Cold War, its geostrategic importance has been diminished. For the US and the EU, challenges have shifted from geopolitical to geo-ideological concerns. In other words, Washington is continuing its crusade for democracy and trade liberalisation, for its benefit, at the level of the Americas, while the European Union is struggling to safeguard the Lomé Agreements and to sign protocols for interregional cooperation with the countries of Latin America. These challenges relate to globalisation, regionalisation and security. This includes drug trafficking, migration, health and meteorological concerns, as well as land and maritime border claims. ; http://www.ifri.org/files/RAMSES_1999/R1999_Partie1.pdf ; National audience for centuries, the Caribbean basin has experienced divergent rivalries and interests between the major European powers. However, since the end of the Cold War, its geostrategic importance has been diminished. For the US and the EU, challenges have shifted from geopolitical to geo-ideological concerns. In other words, Washington is continuing its crusade for democracy and trade liberalisation, for its benefit, at the level of the Americas, while the European Union is struggling to safeguard the Lomé Agreements and to sign protocols for interregional cooperation with the countries of Latin America. These challenges relate to globalisation, regionalisation and security. This includes drug trafficking, migration, health and meteorological concerns, as well as land and maritime border claims. ; National audience Pendant des siècles, le bassin caraïbe a été le théâtre de rivalités et d'intérêts divergents entre les grandes puissances européennes. Mais, depuis la fin de la guerre froide, son importance géostratégique est amoindrie. Pour les États-Unis et l'Union européenne, les enjeux se sont déplacés du domaine géopolitique vers des ...
President Harry S. Truman (1945-1953) claims in 1946 that the U.S. should advance a "faith-based" diplomacy to encourage the spiritual reconstruction of a "dechristianized" Europe .To stand in the way of a Marxist and Godless Soviet Union, it has to begin with France, seen as the spiritual stone arch. More than in any other nation, the Marshall Plan brings a financial, economic and military support, willing to conquer hearts and minds. Many key governmental agencies are involved in this time period, while American churches engaged in aid relief are rediscovering France as a new mission territory. Usually strongly influenced by the religious conviction of the Presidents, "Faith-based policies" supporting Foreign policies are reinforced on the ground by the engagement of private voluntary organizations (PVOs). Formalized in 1998 by President Clinton as a tool in Foreign policy in the enactment of the Act on International Religious Freedom, this approach justifies the tenacity of missionaries from 1945 to the present day in a secular and catholic France. Encouraged by the Fourth Awakening, most American missions, mainstream Protestant churches, new religions like NRM (Mormonism, Adventists, Jehovah's Witnesses, etc.) and Evangelicals, welcome this mixed opportunity: a comeback for a few denominations already presents in the 19th century and for others a chance for a fresh beginning. Although the business of "nation building", the reshaping of the economic and cultural life of France, is perceived by the American public opinion as one of the most disappointing of the post-war, a deeply transformed French society will later emerge. The overlapping of American public and private organizations, of American churches and missionaries lay the groundwork for the radical transformation of a French monolithic religious landscape. Without doubt this can be traced to this short and critical experimental period of the Early Cold War. ; La "Faith-based" diplomatie américaine et les ambiguïtés du plan Marshall : le cas de la ...
President Harry S. Truman (1945-1953) claims in 1946 that the U.S. should advance a "faith-based" diplomacy to encourage the spiritual reconstruction of a "dechristianized" Europe .To stand in the way of a Marxist and Godless Soviet Union, it has to begin with France, seen as the spiritual stone arch. More than in any other nation, the Marshall Plan brings a financial, economic and military support, willing to conquer hearts and minds. Many key governmental agencies are involved in this time period, while American churches engaged in aid relief are rediscovering France as a new mission territory. Usually strongly influenced by the religious conviction of the Presidents, "Faith-based policies" supporting Foreign policies are reinforced on the ground by the engagement of private voluntary organizations (PVOs). Formalized in 1998 by President Clinton as a tool in Foreign policy in the enactment of the Act on International Religious Freedom, this approach justifies the tenacity of missionaries from 1945 to the present day in a secular and catholic France. Encouraged by the Fourth Awakening, most American missions, mainstream Protestant churches, new religions like NRM (Mormonism, Adventists, Jehovah's Witnesses, etc.) and Evangelicals, welcome this mixed opportunity: a comeback for a few denominations already presents in the 19th century and for others a chance for a fresh beginning. Although the business of "nation building", the reshaping of the economic and cultural life of France, is perceived by the American public opinion as one of the most disappointing of the post-war, a deeply transformed French society will later emerge. The overlapping of American public and private organizations, of American churches and missionaries lay the groundwork for the radical transformation of a French monolithic religious landscape. Without doubt this can be traced to this short and critical experimental period of the Early Cold War. ; La "Faith-based" diplomatie américaine et les ambiguïtés du plan Marshall : le cas de la ...
Nations are based on myths, and in the United States, it is the president who is the "storyteller-in-chief" of those sacred stories whose function is to give sense to the existence of the national community. This dissertation offers to examine to what extent the end of the Cold War, which represents a breaking point in the mental representation of the nation, has produced a new discourse in national mythology in presidential speeches. Our research will focus more specifically on the notion that metaphors inform us on the shared beliefs of a given society as cognitive linguistics and critical discourse analysis have largely demonstrated. In our first part, we will concentrate on the myths of virtue and good, and more particularly on the use of religious language which has greatly increased over the period, and on the value of "freedom" that has remained the founding value of the American identity but whose definition has evolved to underline the notion of free will of individuals as opposed to the collective Manifest Destiny rooted in Calvinistic predestination. These myths serve as moral justifications to the rhetoric of power and strength that will be the object of our second part. We will show how the steady presence of war narratives and war metaphors ascribe mythical meaning to violence. Finally, in our third part, we will see how only the heroic narrative illustrates the fusion of the myths of power and virtue and actually constitutes the essential narrative framework in post-Cold War presidential speeches. We will then conclude on the proposition that while the heroic myth may have been fostered by the end of the Cold War, it originated in the rhetoric of Ronald Reagan that might be the most significant breaking point and the beginning of an entire new ideological and political cycle. ; Une nation est toujours fondée sur des mythes. Aux États-Unis, le président est le « conteur-en-chef » de ces récits sacrés qui ont pour fonction de donner du sens à l'existence de la communauté nationale. Cette thèse ...
Nations are based on myths, and in the United States, it is the president who is the "storyteller-in-chief" of those sacred stories whose function is to give sense to the existence of the national community. This dissertation offers to examine to what extent the end of the Cold War, which represents a breaking point in the mental representation of the nation, has produced a new discourse in national mythology in presidential speeches. Our research will focus more specifically on the notion that metaphors inform us on the shared beliefs of a given society as cognitive linguistics and critical discourse analysis have largely demonstrated. In our first part, we will concentrate on the myths of virtue and good, and more particularly on the use of religious language which has greatly increased over the period, and on the value of "freedom" that has remained the founding value of the American identity but whose definition has evolved to underline the notion of free will of individuals as opposed to the collective Manifest Destiny rooted in Calvinistic predestination. These myths serve as moral justifications to the rhetoric of power and strength that will be the object of our second part. We will show how the steady presence of war narratives and war metaphors ascribe mythical meaning to violence. Finally, in our third part, we will see how only the heroic narrative illustrates the fusion of the myths of power and virtue and actually constitutes the essential narrative framework in post-Cold War presidential speeches. We will then conclude on the proposition that while the heroic myth may have been fostered by the end of the Cold War, it originated in the rhetoric of Ronald Reagan that might be the most significant breaking point and the beginning of an entire new ideological and political cycle. ; Une nation est toujours fondée sur des mythes. Aux États-Unis, le président est le « conteur-en-chef » de ces récits sacrés qui ont pour fonction de donner du sens à l'existence de la communauté nationale. Cette thèse propose d'examiner dans quelle mesure la rupture dans l'imaginaire collectif que représente la fin de la guerre froide a engendré une nouvelle rhétorique de la mythologie nationale dans les discours présidentiels. Pour cela, nous nous appuierons sur l'étude de métaphores qui, comme l'ont démontré l'analyse critique du discours et la linguistique cognitive, nous informe sur les croyances collectives d'une société. Dans une première partie, nous nous focaliserons sur les mythes de la vertu et du bien, plus particulièrement sur le langage religieux qui s'est développé dans la période post-guerre froide, et sur la valeur de liberté qui demeure fondatrice de l'identité américaine, mais dont la définition évolue et souligne davantage le libre arbitre de l'individu par opposition au destin manifeste collectif fondé sur la prédestination calviniste. Ces mythes de vertu servent de justification morale à une rhétorique de la puissance et de la force qui fera l'objet de notre analyse dans notre seconde partie. Nous montrerons combien la permanence du récit de guerre et les nombreuses métaphores guerrières rendent compte d'un système de représentation du monde qui donne une signification mythique à la violence. Enfin, dans une troisième partie, nous verrons que seul le récit héroïque illustre l'alliance de la puissance et de la vertu et constitue finalement la trame narrative essentielle du mythe national de l'ère post-guerre froide. Nous conclurons sur la proposition que, si la fin de la guerre froide a favorisé le développement du mythe héroïque dans les discours présidentiels, celui-ci est enraciné dans la rhétorique de Ronald Reagan qui représente le point de rupture le plus significatif dans la production de la mythologie nationale récente ainsi que le point de départ de tout un cycle idéologique et politique.
Au lendemain de la chute de l'Union soviétique, la Central Intelligence Agency (CIA) a pris une initiative d'ouverture, en apparente contradiction avec les us et coutumes d'une agence de renseignement. Au terme de près d'un demi-siècle d'opérations secrètes et de scandales, cette démarche devait permettre de redorer l'image de la communauté du renseignement afin de pouvoir résister aux conséquences potentiellement funestes de la disparition de sa cible originelle. Si la mise en œuvre de ce projet a révélé les difficultés induites par une révolution culturelle de ce type, la CIA est néanmoins parvenue à créer une dynamique favorable à la déclassification de documents d'archive qui a bénéficié à la communauté scientifique. Mais en accroissant la visibilité du renseignement, cette initiative a également servi son instrumentalisation à des fins politiques. ; After the collapse of the Soviet Union, the Central Intelligence Agency (CIA) launched an openness initiative that seemed to contradict the longstanding traditions of intelligence agencies. After almost half a century of secrecy and scandals, this initiative was supposed to rehabilitate the tarnished image of the intelli- gence community and help to keep it afloat despite the potentially disastrous consequences of the disappearance of its initial target. Although the plan's implementation revealed all the difficulties involved in a cultural revolution of this type, the CIA nevertheless succeeded in creating a favourable climate for document declassification that benefited the scientific community. But by increasing the visibility of intelligence gathering, this initiative also contributed to its instrumentalisation for political ends.
National hearing. Among the public scientific controversy, those on the effects of radioactivity are of particular importance because of their regular return to the public scene. This article examines the emergence of such "rebound controversy" by analysing the role of this particular form of controversy in the public formulation of a problem and its political responsibility. He focused on the Cold War period in which the main terms of a debate between science and politics were formulated and paradoxical responses to crisis management were formed. ; Among scientific public controversies, those concerning the effects of radioactivity have a special place due to the fact that they regularly return into the public stage. This article examines the birth of these recurring controversies by analysing the role of this particular form, controversy, in the public formulation of an issue and in its political treatment. It deals especially with the Cold War period during which the principal terms of a debate between science and politics were formulated and paradoxical answers to crisis management were formed. ; National hearing. Among the public scientific controversy, those on the effects of radioactivity are of particular importance because of their regular return to the public scene. This article examines the emergence of such "rebound controversy" by analysing the role of this particular form of controversy in the public formulation of a problem and its political responsibility. He focused on the Cold War period in which the main terms of a debate between science and politics were formulated and paradoxical responses to crisis management were formed. ; National audience Parmi les controverses publiques à caractère scientifique, celles sur les effets de la radioactivité tiennent une place particulière du fait de leur retour régulier sur la scène publique. Cet article examine la naissance de ces « controverses à rebond » en analysant le rôle de cette forme particulière qu'est la controverse dans la formulation publique ...
International audience ; The transformation of humanitarian action during the last decades of the 20th century following the so-called Biafra war, marked the end of the Third World and accompanied the geopolitical reconfiguration of the end of the Cold War. It also transformed the symbolic use of certain musical practices in democracy, some songs becoming part of the communication campaigns by humanitarian organisations following the famine caused by the Ethiopian civil war between 1983 and 1985. This paper analyses the main characteristics of humanitarian songs, considered here as part of larger symbolic political mechanisms, together with the role of these songs in the moralisation process of international relations at the end of the Cold War. ; La transformation de l'action humanitaire dans les dernières décennies du xxe siècle, après la guerre dite du Biafra, marque la fin du tiers-mondisme et accompagne la reconfiguration géopolitique survenue à la fin de la Guerre froide. Elle transforme également l'utilisation symbolique de certaines pratiques musicales en démocratie, des chansons faisant partie des campagnes de communication des organisations humanitaires à partir de la famine provoquée par la guerre civile éthiopienne entre 1983 et 1985. Cet article propose une analyse des principales caractéristiques des chansons humanitaires, considérées ici comme faisant partie de dispositifs de politique symbolique plus larges, et du rôle de celles-ci dans le processus de moralisation des relations internationales à la fin de la Guerre froide.
