When the Old French narrative lays were composed in the second half of the twelfth and during the thirteenth century, the authors had access to the theory of classical rhetoric and medieval poetics. This thesis investigates the correspondences between the relevant theoretical concepts and the arrangement of the lays, and reveals in what manner the authors of the lays employed certain techniques and figures in order to achieve the unity of their works. The research is centred on Geoffrey of Vinsauf's Poetria nova and the Documentum de modo et arte dictandi et versificandi, Matthew of Vendôme's Ars versificatoria, and takes into consideration works of the classical origin, namely the Rhetorica ad Herennium and the Ars poetica of Horace. The analysis comprises the lays Aristote, Conseil, Cor, Desiré, Doon, Espervier, Espine, Graelent, Guingamor, Haveloc, Ignaure, Lecheor, Mantel, Melion, Nabaret, Oiselet, Ombre, Trot, Tydorel and Tyolet. The first four chapters discuss the theory on arrangement, assess the unity of the beginning and end with the body of the texts, and examine to what extent the techniques of abbreviation and amplification emphasize or amplify the overall idea. The remaining three chapters demonstrate important structural features typical of the lay narratives which use various rhetorical and poetic methods. Chapter Five analyzes the lay narratives from the perspective of the figures of wordplay, as well as small and large-scale repetition and parallels. Chapter Six examines the recounting of episodes, which coincides with the amplification technique Refining. Chapter Seven exposes the persuasion and reasoning techniques that the characters employ in order to prove or decide something.

Les exigences de productivité et de qualité dans l’industrie aéronautique imposent d’avoir des machines-outils optimisées en termes de précision, de cinématique et de dynamique. L’objectif des travaux de recherche menés est de proposer de nouvelles méthodologies de conception de machines-outils à haute rigidité pour l’usinage des pièces aéronautique en titane. Dans un premiers temps, la problématique du choix de la configuration structurale la plus adéquate au procédé d’usinage envisagé est traitée en proposant une méthode de synthèse et de sélection basée sur des critères qualitatifs. L’analyse des performances des différentes configurations structurales relatives aux critères qualitatifs adoptés permet de les classer. Les résultats obtenus ont permis d’aboutir à un ensemble restreint de configurations structurales de machines-outils adéquates au procédé d’usinage des pièces aéronautiques en titane. Pour compléter cette méthode, il est alors nécessaire de développer une approche d’analyse quantitative des arrangements structuraux relatifs à chaque configuration structurale. Dans un second temps, une nouvelle approche de sélection des arrangements structuraux de machines-outils est développée. Cette approche consiste tout d’abord à élaborer des modèles réduits des structures de machines-outils considérées. Ensuite, nous mettons en œuvre une optimisation paramétrique en vue de minimiser la masse totale des structures mécaniques de ces machines tout en respectant une contrainte de rigidité cible. Cette optimisation est réalisée par un couplage entre MATLAB et ANSYS APDL. Enfin, le classement des arrangements structuraux selon leurs performances met en évidence ceux les plus appropriés au procédé d’usinage des pièces aéronautiques en titane. Alors ces travaux participent à l'évolution des méthodologies de conception des nouvelles machines d'usinage. / Productivity and quality requirements in the aerospace industry require optimized machine tools in terms of precision, kinematics and dynamics. The objective of this thesis is to propose new methodologies for the design of highly stiffened machine tools for machining titanium aeronautical parts. First, the issue of choosing the most appropriate structural configuration for the machining process is handled by proposing a synthesis and selection method based on qualitative criteria. The performance analysis of the different structural configurations relative to the adopted qualitative criteria makes it possible to classify them. The results obtained have led to a limited set of structural configurations of machine tools suitable for the process of machining titanium aeronautical parts. To complete this method, it is then necessary to develop an approach for quantitative analysis of the structural arrangements corresponding for each structural configuration. In a second step, a new approach for the selection of structural arrangements of machine tools is developed. This approach consists firstly in developing reduced models of considered machine tool structures. Then, we implement a parametric optimization in order to minimize the total mass of the mechanical structures of these machines while under the constraint of a target stiffness. This optimization is achieved by coupling MATLAB and ANSYS APDL. Finally, the classification of structural arrangements according to their performance highlights those most appropriate for the process of machining titanium aeronautical parts. This work contributes to the evolution of design methodologies for new machining machines.