Designing redundant metering valves for hydraulic actuators under mixability and low cost-constraints

This article deals with the design of redundant metering valves for mechanically signalled hydraulic actuators. The final aim of the work is to manufacture a new low-cost valve in replacement of the existing expensive valve with an additional leakage requirement in case of seizure. The new valve must ensure the same closed-loop behaviour of the actuator. The article presents the design of the valve according to the actuator specifications and to a criterion of mixability (capacity to replace the existing valve by a new one). The valve pre-design is based on the common sharp edges and rectangular orifice slots combined with a serial restrictor inserted on the supply line. After partial experimental validation, the proposed design process points out the interest of using a trapezoidal slot in order to get the required speed gain over the whole valve opening range. The proposal is validated through the experimental measurement of the actuator no-load speed as a function of the valve opening

Integration and communication of CSR principles by IKEA. An analysis of the influence of and on external stakeholders

In spite of the rising influence of NGOs, the impact of CSR implementation and communication on NGOs’ perceptions and attitudes is rarely evoked. Moreover, empirical studies generally take into account one category of stakeholder at a time, preventing analysts from examining the likely differential impacts of CSR on distinct categories of stakeholders. In this context, this paper proposes (1) to analyze how different external and ubiquitous stakeholders can influence the development of CSR commitments and (2) to assess the impact of CSR commitments and communications on those stakeholders, by using an integrative framework aimed at providing an integrated stakeholder orientation for a step by step implementation of CSR (Maignan et al., 2005). Our analyses are based on an in-depth case study of IKEA and its main stakeholders: trade unions, customers, partner NGOs, organizations having blamed IKEA on CSR matters, local public authorities, organizations protecting small businesses, and specialized organizations dedicated to consultancy, promotion, and monitoring of CSR practices. Because of its continuous pressure on price and sub-contractors from developing countries, IKEA stands in a good position to run up against the sensitivity of alter globalization protesters. But in the same time, IKEA is seldom blamed on its CSR practices. Our results show how stakeholders can influence the development of CSR policies by conveying their societal expectations, by publicly blaming corporate behaviours considered as irresponsible or by entering in a collaborative and constructive relationship with the company. This case study also highlights the complexity of the corporate decisions related to CSR practices and communication, as well as the central role played by scepticism in the construction of CSRbased attitudes towards the company. By not involving stakeholders enough, IKEA’s CSR policy is gauged as too unilateral, what leads to a certain stakeholders’ scepticism about IKEA’s CSR practices. And IKEA is criticized for adopting a low profile in terms of CSR communication

Facing the challenge of predicting the standard formation enthalpies of n-butyl-phosphate species with ab initio methods

Tributyl-phosphate (TBP), a ligand used in the PUREX liquid-liquid separation process of spent nuclear fuel, can form explosive mixture in contact with nitric acid, that might lead to violent explosive thermal runaway. In the context of safety of a nuclear reprocessing plant facility, it is crucial to predict the stability of TBP at elevated temperatures. So far, only the enthalpies of formation of TBP is available in the literature with a rather large uncertainties, while those of its degradation products, di-(HDBP) and mono-(H$_2$MBP}) are unknown. In this goal, we have used state-of-the art quantum chemical methods to compute the formation enthalpies and entropies of TBP and its degradation products di-(HDBP), mono-(H$_2$MBP) in gas and liquid phases. Comparisons of levels of quantum chemical theory revealed that there are significant effects of correlation on their electronic structures, pushing for the need of not only high level of electronic correlation treatment, namely local coupled cluster with single and double excitation operators and perturbative treatment of triple excitations [LCCSD(T)], but also extrapolations to the complete basis to produce reliable and accurate thermodynamics data. Solvation enthalpies were computed with the conductor like screening model for real solvents [COSMO-RS], for which we observe errors not exceeding 22 kJ mol$^{-1}$. We thus propose with final uncertainty of about 20 kJ mol$^{-1}$ standard enthalpies of formation of TBP, HDBP, and H$_2$MBP which amounts to -1281.7$\pm$24.4, -1229.4$\pm$19.6 and -1176.7$\pm$14.8 kJ mol$^{-1}$, respectively, in the gas phase. In the liquid phase, the predicted values are -1367.3$\pm$24.4, -1348.7$\pm$19.6 and -1323.8$\pm$14.8 kJ mol$^{-1}$, to which we may add about -22 kJ mol$^{-1}$ error from the COSMO-RS solvent model. From these data, we predict the complete hydrolysis of TBP to be nearly thermoneutral

Les critiques d'art contemporain : petit monde éditorial et économie de la gratuité

L’article propose de retracer les carrières des critiques d’art contemporain et de montrer comment celles-ci produisent une morphologie singulière de l’espace des revues traitant d’art contemporain depuis la fin des années 1990. Il montre que les carrières se déroulent en trois temps : celui de la vocation, celui d’une activité frénétique qui les voit, en vain, tenter de gagner leur vie de leur activité d’écriture, et celui enfin, beaucoup plus long, au cours duquel les critiques se consacrent à une autre activité, souvent au sein du monde de l’art. En nous appuyant sur l’analyse de réseau, nous montrons comment ces carrières ternaires nourrissent une structure éditoriale de type centre-périphérie. L’article propose, pour finir, une explication rendant compte de l’existence et de la stabilité de ce régime de la gratuité.This article undertakes to retrace the careers of contemporary art critics. It shows how these careers have contributed to forming the singular morphology of the place of contemporary art magazines since 1990. It shows that careers develop in three steps: the vocation, followed by frenzied activity as they try – in vain – to earn a living from their writing, and, lastly, the much longer period when critics devote themselves to another occupation, usually within the art world. Using network analysis as a basis, we show how these threefold careers have played a part in shaping up the structure of this area of the publishing world, which is of the centre-periphery type. Finally, this article puts forward a possible explanation for the existence and stability of the ecosystem of the free of charge