Liquid lubrication in sheet metal forming at mesoscopic scale

The lubricant entrapment and escape phenomena in metal forming are studied experimentally as well as numerically. Experiments are carried out in strip reduction of aluminium sheet applying a transparent die to study the fluid flow between mesoscopic cavities. The numerical strategy is based on a weak fluid/structure coupling involving the Finite ElementMethod and analytical calculations. It allows to quantify the final shape of the lubricant pocket

Roughness Signature of Tribological Contact Calculated by a New Method of Peaks Curvature Radius Estimation on Fractal Surfaces

This paper proposes a new method of roughness peaks curvature radii calculation and its application to tribological contact analysis as characteristic signature of tribological contact. This method is introduced via the classical approach of the calculation of radius of asperity. In fact, the proposed approach provides a generalization to fractal profiles of the Nowicki's method [Nowicki B. Wear Vol.102, p.161-176, 1985] by introducing a fractal concept of curvature radii of surfaces, depending on the observation scale and also numerically depending on horizontal lines intercepted by the studied profile. It is then established the increasing of the dispersion of the measures of that lines with that of the corresponding radii and the dependence of calculated radii on the fractal dimension of the studied curve. Consequently, the notion of peak is mathematically reformulated. The efficiency of the proposed method was tested via simulations of fractal curves such as those described by Brownian motions. A new fractal function allowing the modelling of a large number of physical phenomena was also introduced, and one of the great applications developed in this paper consists in detecting the scale on which the measurement system introduces a smoothing artifact on the data measurement. New methodology is applied to analysis of tribological contact in metal forming process

Productive restructuring and the reallocation of work and employment: a survey of the “new” forms of social inequality

O propósito do presente artigo consiste em questionar a inevitabilidade dos processos de segmentação e precarização das relações de trabalho e emprego, responsáveis pela inscrição de “novas” formas de desigualdade social que alicerçam o actual modelo de desenvolvimento das economias e sociedades. Visa-se criticar os limites da lógica econômica e financeira, de contornos globais, que configuram um “novo espírito do capitalismo”, ou seja, uma espécie de divinização da ordem natural das coisas. Impõe-se fazer, por isso, um périplo analítico pelas transformações em curso no mercado de trabalho, acompanhado pela vigilância epistemológica que permita enquadrar e relativizar as (di)visões neoliberais e teses tecnodeterministas dominantes. A perspectivação de cenários sobre o futuro do trabalho encerrará este périplo, permitindo-nos alertar para os condicionalismos histórico-temporais, para a urgência de se desocultar o que de ideológico e político existe nas actuais lógicas de racionalização e para os processos de ressimbolização do trabalho e emprego enquanto “experiência social central” na contemporaneidade.The scope of this paper is to question the inevitability of the processes of segmentation and increased precariousness of the relations of labor and employment, which are responsible for the introduction of “new” forms of social inequality that underpin the current model of development of economies and societies. It seeks to criticize the limits of global financial and economic logic, which constitute a “new spirit of capitalism,” namely a kind of reverence for the natural order of things. It is therefore necessary to conduct an analytical survey of the ongoing changes in the labor market, accompanied by epistemological vigilance which makes it possible to see neoliberal (di)visions and dominant technodeterministic theses in context. The enunciation of scenarios on the future of work will conclude this survey and will make it possible to draw attention to both the historical and temporal constraints and to the urgent need to unveil what is ideological and political in the prevailing logic of rationalization and processes to reinstate work and employment as a “central social experience” in contemporary times

Modélisation des écoulements souterrains entre interfluves et bas-fonds rizicoles : cas d'un bassin versant élémentaire des hauts plateaux malgaches

Le bassin versant d'Ambohitrakoho fait l'objet d'un suivi métrologique de plusieurs années, dans le cadre d'un programme de collaboration franco-malgache inscrit dans l'action thématique "Bilans en eaux" du CNRS. Les données partielles sont examinées pour apprécier les modalités du fonctionnement hydrique des différents compartiments du système complexe formé du socle granitique faillé, de matériaux altéritiques, de sables lavés et matériaux d'origine anthropique, liés à l'exploitation rizicole du bas-fond. Le rôle de ces grands compartiments est apprécié grâce à une modélisation numériques des écoulement souterrains basée sur un schéma conceptuel en plans multicouche. On propose d'étudier le rôle spécifique de l'horizon sableux lavé présent dans le bas-fond au moyen d'un second modèle, en plan vertical, pour préciser la distribution verticales des flux échangés entre l'eau superficielle et l'eau souterraine. Des tests de sensibilité sont conduits et un éventail de mesures complémentaires in situ est proposé pour améliorer le calage des modèles qui, dans leur état actuel, restent trop approximatifs pour être appliqués à la gestion du bassin

A identidade de policiais civis e sucessivos espelhamentos

Objetivou-se analisar as percepções de policiais civis sobre a sua identidade profissional e a instituição na qual atuam, bem como a sua opinião acerca da imagem que a sociedade tem sobre a sua atuação. Os dados provêm de uma pesquisa sobre condições de trabalho e saúde dos policiais civis da Baixada Fluminense, com questionário, entrevistas e grupos focais, envolvendo gestores, delegados e policiais das 18 delegacias da área, mais uma especializada. Neste estudo, calcularam-se as frequências relativas e médias das respostas sobre condições de trabalho, satisfação e melhoria da qualidade de vida após ingressar na instituição. Selecionaram-se questões qualitativas acerca da opinião dos profissionais sobre como a sociedade percebe a polícia civil e o que é ser policial na Baixada Fluminense, efetuando-se a análise segundo o método de interpretação de sentidos. Os resultados apontam para uma imagem negativa que os policiais julgam que a sociedade tem sobre eles, o que implica e reforça uma desvalorização da profissão. Eles recusam essa identificação negativa e procuram diferenciar o ser policial civil do ser policial militar. Não se observam especificidades quanto a ser policial na Baixada Fluminense. Conclui-se que são necessárias ações que melhorem as condições de trabalho, o diálogo com as comunidades e que promovam ações de saúde

Evolution of the ridges of Midelt-Errachidia section in the High Atlas revealed by paleomagnetic data

New paleomagnetic data (43 sites) from Mesozoic sediments are contributed in this work, verifying the presence of a pervasive syntectonic Early Cretaceous remagnetization in the easternmost area of the Moroccan High Atlas. Using the small circle intersection method, we have calculated the characteristic remagnetization direction (Dec: 337.3, Inc: 38.4) that fits with a 100-Ma age, according to the Apparent Polar Wander Path of Africa. The paleomagnetic vectors of remagnetization are used to obtain the geometry during the remagnetization stage (100Ma) of one of the most renowned geological cross sections of the High Atlas, the Midelt-Errachidia profile. The partial restoration of the cross section at 100Ma allows us to determine the dips of the beds at the remagnetization stage in five structures (ridges or anticlines). Our results indicate that the five ridges that configure the Midelt-Errachidia profile were initiated to different degrees prior to wholesale compressive deformation during the Cenozoic. This configuration can be explained according to two different scenarios that we discuss in this paper: transpression and diapirism. The geological model obtained, both at present and at 100Ma, indicates the existence of a Mesozoic cover substantially decolled from the Paleozoic basement, what strongly contrasts with previously published transects of the same area