Développement d'un modèle d'efforts de coupe multi-opérations et multi-matériaux. Application au tournage du cuivre pur dans différents états métallurgiques.

La modélisation des efforts de coupe en usinage est nécessaire pour prédire certaines caractéristiques de la pièce usinée comme sa géométrie, son état de surface ou encore l'intégrité de la matière en sub-surface.Les nombreux modèles d'efforts de coupe déjà développés sont souvent appliqués dans le cas d'opérations d'usinage simples, ce qui limite leur diffusion vers le milieu industriel, alors qu'il existe un réel besoin de modélisation d'opérations d'usinage complexes et variées, et prenant en compte d'éventuels changements métallurgiques au niveau du matériau usiné.L'objectif de ces travaux est de proposer un modèle d'efforts de coupe appliqué à toute opération de tournage d'une part et considérant certaines propriétés mécaniques du matériau usiné d'autre part.Concernant l'aspect multi-opérations, un modèle géométrique utilisant des transformations homogènes a été développé et permet de décrire à la fois la trajectoire et la géométrie de l'outil. Les effets de paramètres originaux, tels que le diamètre de la pièce, l'angle de direction d'arête et le rayon de bec, sont étudiés, notamment à l'aide de nouvelles configurations de coupe élémentaires. La prise en compte de ces paramètres dans les relations de coupe locales permet finalement d'améliorer la simulation des efforts de coupe lors d'un contournage.L'approche utilisée pour l'aspect multi-matériaux consiste à modifier progressivement le matériau usiné. Ainsi, le matériau initial, le cuivre pur, a été étudié dans différents états métallurgiques, obtenus par des traitements thermo-mécaniques. En particulier, le procédé d'extrusion coudée à aires égales (ECAE) a été utilisé afin d'écrouir le matériau dans la masse. Ainsi, trois matériaux aux caractéristiques mécaniques différentes mais conservant plusieurs caractéristiques communes (thermiques notamment) ont pu être comparés en termes d'efforts de coupe. Les coefficients des relations de coupe sont finalement mis en regard des propriétés mécaniques obtenues par des essais de traction et de compression à grande vitesse.The cutting forces have to be known as accurately as possible in order to predict the characteristics of the workpiece as the geometry, the roughness or the material integrity.Numerous models have been yet developed; however, the majority cannot be used for the various industrial cutting operations and remain confined for a single machined material.The objective of this study is to develop a cutting forces model applied to any turning operation and taking into account some mechanical characteristics of the machined material.First, a geometrical model based on homogeneous transformations is presented. Then, the effects of some parameters, like the workpiece diameter, the cutting edge angle and the nose radius, are studied by using new cutting configurations, in order to improve the cutting laws.The multi-material aspect is approached by modifying the metallurgical state with thermo-mechanical treatments, especially by using the equal channel angular extrusion process in order to harden the material in the mass. Finally, the coefficients of the local cutting relations are compared to mechanical characteristics obtained from tensile and high compression tests.PARIS-Arts et Métiers (751132303) / SudocSudocFranceF

Parkia biglobosa (Leguminosae) en Afrique de l'Ouest : biosystematique et amelioration

The purpose of the research presented here is to strengthen the scientific and technical basis of biodiversity conservation, and use of Parkia biglobosa (African locust bean, néré ). The approach to this research included the gathering of technical and ethnobotanical data. This information can be used to support the development of methods and strategies for conservation, use and improvement of this multi-purpose agroforestry tree species in West and Central Africa.Overexploitation of land, particularly in densely populated and dry areas, affects the rejuvenation process of this tree. This results in the general aging of néré orchards, particularly in the southern part of its range of distribution.More than 1600 trees from 5 countries were sampled and various morphometric and phenological observations were used to determine the level of the variation extant in P . biglobosa as well the structure of this diversity. Socio-economic and cultural data were obtained through questionnaires filled out by more than 500 people from different ethnicgroups in Burkina Faso and Benin.The initial hypothesis of the research was: a number of phenotypic characters of the species present clinal variation along longitudinal and latitudinal gradients. This has important implications for selection, conservation and genetic improvement.The research established the place and importance of néré in the daily life of many rural communities and determined the kinds of variation in P. biglobosa and how to capture this variation in an efficient way. This rich traditional knowledge presents a social image of the tree, as a common resource, which reinforces the cohesion of the group and is a symbol of peace, continuity, and harmonious development in these communities.Every part of this multi-pupose tree is utilized. The tree functions to diversify production and sources of income in the agricultural system. The fermented seeds produce a protein-rich condiment, soumbala or dawadawa, that fortifies the taste of most sauces. The pulp around the seeds is rich in sugar and is much appreciated by children. Bark and leaves, as well as seeds and pulp, have medicinal properties and are used in the treatment of more than 40 ailments.Almost every community has a different local name for the tree. Ibis linguistic diversity reflects ancient traditional knowledge about the species. The numerous customs, rites, legends and folklore are evidence of the existence of profound, durable and harmonious interdependence and mutual benefit between persons in the village and trees in the orchard. This knowledge is based on a large number of the tree characteristics such as adaptation, various uses, vigour, resistance to pests and specific diseases, bark texture and fruit production capacity (quantity, quality and periodicity). Various forms of néré are distributed in correlation to the enviromnental conditions.Women, who are the most knowledgeable about the tree, are the repository of the knowledge concerning fruit and seed aspects. They handle the seeds, exchange plant material and prepare the food items. The men maintain the knowledge on sylvicultural practices to optimize production. This includes balancing interaction between the tree and crops to avoid crop pests and diseases. Future collecting of plant material should take into account the importance of the traditional knowledge that contributes to the maintenance of intra- and inter- population diversity. nis concerns vernacular names, tree appearance, fruit production capacity, medicinal properties, origins and particular enviromnental conditions.The variation between individual trees is large, but the variation between populations is relatively small as is the variation between countries. The nature, the level and the structure of the phenotypic diversity observed in P . biglobosa is the result of several factors, among which are genetics and environment.The tree architecture is flexible and approaches the model of Champagnat; it adapts to enviromnental factors, as is the case of many of the Leguminosae. The species has developed various adaptive strategies that are reflected in its phenology and reproductive system. Leaves are always present, but gradually fall in the last weeks before the new leaves unfurl.Vegetative and reproductive parts are in competition for available energy sources. The onset of flowering is staggered from south to north, from November-December in the south to late March in the north, creating a difference of 3 to 4 months. As a consequence, fruiting is staggered too, from March in the south to July in the north. In contrast, in a east-west direction, staggering of flowering and fruiting is less, only about two weeks. Phenological variation along the latitudinal gradient is gradual. Rainfall and subsequent availability of water in the soil plays an important, but not exclusive, role in determining leaf production and flowering. The large individual phenological variations seem to be correlated to very localized soil conditions and to the genotype of individual trees.The reproductive system is allogamous by preference, but autogamy is always possible, even if limited by self-incompatibility. Bees constitute (in Burkina Faso) the main pollinators, together with bats. The activity of bats in the southern region is more important. The pollinators influence fruit set and the structure of inter-population diversity. Man strongly contributes to changes in the level and structure of intra- and inter-population diversity. His practices are very important in the savanas and are related to the importance ascribed to the tree. In forest zones the tree is valued relatively little.Because of the importance of P. biglobosa, it is necessary to deploy national, regional and international research and development to assure its conservation and genetic improvement. It is also needed to promote traditional cultivation practices to profit most of the available resources and to increase production in the existing agricultural system.Given the distribution of observed phenetic diversity, selection of a maximum of individuals from a limited number of populations at the country level, and of some populations on the regional level, represents an adequate strategy to capture a maximum of genetic diversity. Indigenous knowledge, favouring the role of women when aquiring these data, is indispensable to improve the selection. The on-going research to understand the level and the structure of inter- and intraspecific genetic diversity will no doubt supply useful additional information

Top-Managers of Foreign Multinational Enterprises in Mexico : Socialization, Leadership Style and Impact

This study focuses on the top-managers who run the subsidiaries of foreign multinational enterprises (MNEs) in Mexico. While some of them are Mexican, others are foreigners who have been sent from the countries of origin of their enterprises. The thesis explores and compares the socialization, worldviews, values, identities and social distinction practices of these top-managers and investigates the intercultural interactions, identity, struggles and communication problems between Mexican and expatriate managers. In addition, the relationship and misunderstandings between foreign managers and local workers are taken into account. Furthermore, the impact of foreign multinational enterprises and foreign business elites on their local employees, their families and communities, and on Mexican society as a whole is examined. The question Are foreign multinational enterprises and elites agents of cultural and institutional change and, if so, which impact do they have on Mexican society? is addressed

CORPORATE SOCIAL RESPONSIBILITY IN ROMANIA

The purpose of this paper is to identify the main opportunities and limitations of corporate social responsibility (CSR). The survey was defined with the aim to involve the highest possible number of relevant CSR topics and give the issue a more wholesome perspective. It provides a basis for further comprehension and deeper analyses of specific CSR areas. The conditions determining the success of CSR in Romania have been defined in the paper on the basis of the previously cumulative knowledge as well as the results of various researches. This paper provides knowledge which may be useful in the programs promoting CSR.Corporate social responsibility, Supportive policies, Romania

P14.02 An electronic behaviour diary: Monitoring the effects of advanced obstetric surgical skills training

Objective: Training should lead to improvements in the quality of clinical care delivery. It is essential to follow up participants after a training intervention to monitor changes in behaviour associated with adoption of lessons learned into clinical practice. We introduced an electronic diary to facilitate monitoring whilst minimising effort for participants. Method: An electronic diary was created using a freely available on-line platform. Following a training intervention on advanced obstetric surgical skills, obstetric residents from Kenya were invited to pilot completing the diary after their labour ward shifts. Entries were anonymised. Participants were asked to enumerate the times they utilised specific skills, or to state why they had been unable to do so, using tick box options. Reflections on skills used were entered using free comments. Results: All participants reported changed behaviours, for example, improved surgical knot-tying, safer needle handling, separate closure of uterine incision angles and techniques for delivery of the impacted fetal head. 6 reported conducting vaginal breech birth and 6 performed vacuum-assisted birth. All reported improvements in use of the safe surgical checklist, obtaining consent and respectful maternity care. 7 had participated in newborn resuscitation. Reflections suggested participants experienced improved levels of confidence and satisfaction when implementing new skills. Conclusion: This pilot study has demonstrated the feasibility of monitoring clinical behaviour change following training using an electronic platform. Monitoring the effect of training is essential to prove that training results in improvements to clinical practice. We plan to roll out this intervention following future training interventions