La grandeza de Louis Josserand. Fuerzas y flaquezas de un civilista de provincias en la IIIª República francesa

Louis Josserand está en el candelero. Varios estudios le han sido consagrados recientemente y los dos volúmenes de sus Essais de téléologie juridique acaban de ser oportunamente reeditados en Éditions Dalloz a cargo de David Deroussin. La mayor parte de los trabajos dedicados al profesor lionés pertenecen al ámbito de la historia de las ideas: se refieren a su pensamiento jurídico, a la extensión de su “influencia” e incluso a los presupuestos ideológicos que la fundan. Este enfoque se esfuerza por reconstruir la coherencia de los enunciados producidos por el autor, trata de seguir los meandros de su pensamiento para apoderarse de cualquier sutileza. Desde esa perspectiva, si Josserand puede ser elevado a la dignidad de “gran jurista” es debido a la fuerza de su argumentación ya la pertinencia de sus análisis. [Premières lignes

Oligocene-Miocene burial and exhumation of the Southern Pyrenean foreland quantified by low-temperature thermochronology

International audienceThe central Pyrenees experienced an episode of rapid exhumation in Late Eocene-Early Oligocene times. Erosional products shed from the range during this time were deposited in large palaeovalleys of the southern flank of the Axial Zone, leading to significant sediment accumulation. A recent numerical modelling study of the post-orogenic exhumation and relief history of the central Axial Zone allowed us to constrain this valley-filling episode in terms of timing and thickness of conglomeratic deposits. This paper aims to test these results for the southern fold-and-thrust belt using apatite fission-track and (U-Th)/He analysis on detrital samples from the Tremp-Graus and Ager basins. inverse thermal-history modelling of the low-temperature thermochronology data indicates that the fold-and-thrust belt was covered during the Late Eocene to Miocene by 0.7-1.6 km of sediments and confirms the timing of re-excavation of the valleys during the Miocene. A detailed analysis of the apatite (U-Th)/He results shows that the significant scatter in grain ages can be explained by the influence of alpha-recoil damage with varying effective uranium content together with distinct pre-depositional thermal histories; the age scatter is consistent with initial exhumation of the sediment sources during the Triassic and Early Cretaceous

The work on hydrodynamic journal bearings carried out at Minho University in the last 30 years

The hydrodynamic journal bearing is still one of the most geometrically simple mechanical components, yet highly reliable and efficient and, above all, unique in what concerns to heavy duty – high load, high speed – support of rotating shafts. Analytical studies, not only to understand the physical basis of its performance, but also to develop practical tools for an expedite design, as well as to assure its reliability and improved efficiency, were object of the early developments in fluids’ hydrodynamic sciences, since the late XIX century, and are still been refined and improved on the XXI century. Historical marks can be flagged as (i) simplified analytical resolutions of the hydrodynamic pressure distribution; (ii) computerized iterative resolution of the full pressure development equations; (iii) introduction of the lubricant feeding conditions; (iv) analysis of the thermal aspects and its influence on viscosity; (v) localized aspects of fluid flow, due to thermal/viscous phenomena and geometrical particularities. This evolution led to increased accuracy on the performance predictions and to safer and higher efficiency of the designed components. On the other hand, analysis became more specific in use and, particularly with the introduction of the thermo-hydrodynamic analysis, led to the need of ‘tailored’ solutions to a given set of specific conditions. As a consequence, methods lost much of their ‘universality’ and ease of use to the common and sporadic designer. This work intents to make a first evaluation of the response of three prediction methods – a commercial and widely used isothermal approach and an isothermal and a thermohydrodynamic procedures, these former developed at UMinho over the last years – in an attempt to highlight the variability of the predictions of the main performance parameters by the use of simpler and rapid methods, when compared with those based on more complex and accurate analysis, and their eventual influence on an efficient and reliable design solution

The role of lubricant feed temperature on the performance of twin groove journal bearings : an experimental study

An experimental assessment of the influence of lubricant feed temperature (Tf) on the behaviour of twin groove hydrodynamic journal bearings has been undertaken. Several loads, shaft speeds and bearing geometries were tested under constant lubricant feed pressure (pf), while Tf took four different values between 29ºC and 58ºC. It was found that the increase of Tf has an effect in bearing performance which is analogous in many ways to the effect of the increase in eccentricity: increase in lubricant flow rate (especially in the low eccentricity range), in outlet temperature (Tout) and in maximum bush temperature (Tmax). Nevertheless, the latter increase was lower than the corresponding increase in Tf. Also, in the high eccentricity range the increase in flow rate due to the increase of Tf could be deceiving in the sense that the additional flow was supplied mainly to the inactive region of the bearing (the unloaded land of the bearing).Fundação para a Ciência e a Tecnologia (FCT

Temperature, flow and eccentricity measurements in a journal bearing with a single axial groove at 90º to the load line

Parametric experiments have been conducted to analyse the influence of some supply conditions on the performance of a steadily loaded journal bearing. Temperature distribution on the internal surface, flowrate and bearing eccentricity were measured for different sets of operating conditions, at variable supply conditions. Quantitative information is provided which shows the effect of both shaft speed and applied load on maximum bush temperature and flowrate. It has been observed that flowrate was modestly affected by load and significantly affected by rotational speed, oil supply temperature and supply pressure. Maximum bush temperature was modestly affected by supply pressure, moderately affected by load and significantly affected by shaft speed. For low applied loads, the attitude angle was markedly affected by supply pressure. The experimental results also showed that for a small groove length there is a variation of bush temperature in axial direction in the groove region.Fundação para a Ciência e a Tecnologia (FCT) - PRAXIS XXI Programme/BD/13922/9

On the occurrence of negative groove flow rate in twin groove hydrodynamic journal bearings

This paper describes the phenomenon of negative flow rate (hot oil reflux) occurring in one of the grooves of twin axial groove hydrodynamic journal bearings. This rarely described phenomenon, which can occur under severe operating conditions, increases the risk of bearing seizure. Existing codes for predicting bearing behaviour do not seem to be suitably incorporating this phenomenon into the analysis. The present work reports some experimental observations of the phenomenon and the way it can be taken into account in theoretical modelling.FCT - POCTI/39202/EME/2001 & PhD grant SFRH/BD/22278/200