The fusion approach – applications for understanding local government and European integration

The article explores the theoretical capabilities of the fusion approach as a conceptual ‘kit’ to explain the ‘bigger picture’ of European integration from a local government perspective. Fusion addresses the rationales and methods facilitating the transfer of policy-making competences to the European level. It understands European integration as a merging of public resources and policy instruments from multiple levels of government, whereby accountability and responsibilities for policy outcomes become blurred. The article argues that the fusion approach is useful to explain the systemic linkages between macro-trajectories and the corresponding change at the local level; the fusion dynamics of the local and European levels in a common policy-cycle; and the attitudes of local actors towards the EU. Although the article concludes that local government is rather modestly ‘fused’ into the EU, fusion approaches allow examining the extent to which the local level has become integrated into the European governance system

Strength-ductility behaviour of Al-Si-Cu-Mg casting alloys in T6 temper

A comparative study of the mechanical properties of 20 experimental alloys has been carried out. The effect of different contents of Si, Cu, Mg, Fe and Mn, as well as solidification rate, has been assessed using a strength-ductility chart and a quality index-strength chart developed for the alloys. The charts show that the strength generally increases and the ductility decreases with an increasing content of Cu and Mg. Increased Fe (at Fe/Mn ratio 0.5) dramatically lowers the ductility and strength of low Si alloys. Increased Si content generally increases the strength and the ductility. The increase in ductility with increased Si is particularly significant when the Fe content is high. The charts are used to show that the cracking of second phase particles imposes a limit to the maximum achievable strength by limiting the ductility of strong alloys. The (Cu + Mg) content (at.%), which determines the precipitation strengthening and the volume fraction of Cu-rich and Mg-rich intermetallics, can be used to select the alloys for given strength and ductility, provided the Fe content stays below the Si-dependent critical level for the formation of pre-eutectic alpha-phase particles or beta-phase plates

Mass balance characterisation of Al-7Si-Mg alloy microstructures as a function of solution treatment time

Mass balance calculations were performed to model the effect of solution treatment time on A356 and A357 alloy microstructures. Image analysis and electron probe microanalysis were used to characterise microstructures and confirm model predictions. In as-cast microstructures, up to 8 times more Mg is tied up in the pi-phase than in Mg2Si. The dissolution of pi is accompanied by a corresponding increase in the amount of beta-phase. This causes the rate of pi dissolution to be limited by the rate of beta formation. It is predicted that solution treatments of the order of tens of minutes at 540degreesC produce near-maximum T6 yield strengths, and that Mg contents in excess of 0.52 wt% have no advantage

The Europeanization of UK Government: From Quiet Revolution to Explicit Step-Change?

In this paper we review - from a UK perspective - how the UK government and its policy process have adapted to European integration. Has adaptation been a quiet revolution, a step-change, or both? In exploring this puzzle we draw upon the conceptual literature of Europeanisation. We employ it to shed light on the longer-term pattern of UK adaptation as well as to put into context the domestic changes currently under way. Although commentators frequently alight upon continued non-membership of the euro as an indicator of the UK's continued incomplete adaptation to integration, we argue that there is a step-change under way in the Europeanisation of UK EU policy making, though not necessarily in its outcomes

Quench Sensitivity in a Dispersoid-Containing Al-Mg-Si Alloy

The quench sensitivity of a 6000 series alloy with a high content of dispersoids was studied over a wide range of cooling rate and natural-aging (NA) time. Positron annihilation lifetime spectroscopy, differential scanning calorimetry, and transmission electron microscopy were used to characterize the clustering and precipitation reactions. The alloy showed significant quench sensitivity after short NA (2 and 30 minutes), but the quench sensitivity was lower after long NA (24 hours). The quench sensitivity after the long NA can be accounted for by the solute loss due to the formation of nonhardening β′ precipitates on the dispersoids during cooling from solution treatment. For short NA, however, quenched-in vacancies and modifications to the precipitation sequence also have substantial contributions to the quench sensitivity. The current study provides new insight into the quench sensitivity of 6000 series alloys that contain a high dispersoid density

Migration of Jupiter-mass planets in low-viscosity discs

International audienceContext. Type-II migration of giant planets has a speed proportional to the disc’s viscosity for values of the α viscosity parameter larger than 10−4. Previous studies based on two-dimensional simulations, have shown that, at even lower viscosities, migration can be very chaotic and is often characterised by phases of fast migration. The reason is that vortices appear in low-viscosity discs due to the Rossby-wave instability at the edges of the gap opened by the planet. Migration is then determined by vortex-planet interactions.Aims. Our goal is to study giant planet migration in low-viscosity discs with 3D simulations. In 3D, vortices are more complex than the simple vertical extension of their 2D counterparts; their impact on planet migration is therefore not obvious.Methods. We performed numerical simulations using two grid-based codes: FARGOCA for three-dimensional simulations and FARGO-ADSG for the two dimensional case. Two-dimensional simulations were used mainly for preliminary tests to check the impact of self-gravity on vortex formation and on vortex-disc dynamics. After selecting disc masses for which self-gravity is not important at the planet location, three-dimensional simulations without self-gravity can be safely used. We have considered an adiabatic equation of state with exponential damping of temperature perturbations in order to avoid the development of the vertical shear instability. In our nominal simulation, we set α = 0 so that only numerical viscosity is present. We then performed simulations with non-zero α values to assess the threshold of prescribed viscosity below which the new migration processes appear.Results. We show that for α ≲ 10−5 two migration modes are possible, which differ from classical Type-II migration in the sense that they are not proportional to the disc’s viscosity. The first occurs when the gap opened by the planet is not very deep. This occurs in 3D simulations and/or when a big vortex forms at the outer edge of the planetary gap, diffusing material into the gap. The de-saturation of co-orbital and co-rotation resonances keeps the planet’s eccentricity low. Inward planet migration then occurs as long as the disc can refill the gap left behind by the migrating planet, either due to diffusion caused by the presence of the vortex or to the inward migration of the vortex itself due to its interaction with the disc. We call this type of migration ‘vortex-driven migration’, which differs from ‘vortex-induced’ migration described in Lin & Papaloizou (2010, MNRAS, 405, 1473, and 2011a, MNRAS, 415, 1445). This migration is very slow and cannot continue indefinitely because eventually the vortex dissolves. The second migration mode occurs when the gap is deep so that the planet’s eccentricity grows to a value e ~ 0.2 due to inefficient eccentricity damping by co-rotation resonances. Once the planet is on an eccentric orbit, gas can pass through the gap and planet migration unlocks from the disc’s viscous evolution. This second, faster migration mode appears to be typical of two-dimensional models in discs with slower damping of temperature perturbations.Conclusions. Vortex-driven migration in low-viscosity discs can be very slow and eventually reverses and stops, offering an interesting mechanism to explain the existence of the cold-Jupiter population, even if these planets originally started growing at the disc’s snowline

Grain refinement of laser remelted Al-7Si and 6061 aluminium alloys with Tibor® and scandium additions

One of the challenges facing additive manufacturing is the current lack of control over the microstructure that forms during the process. Typically, the rapid cooling rates and steep thermal gradients in the melt pool encourages epitaxial columnar grain growth. In this paper the effectiveness of scandium and TiBor grain refiners in controlling the microstructure during laser melting of aluminium alloys (Al-7Si and 6061) is investigated. Electron Backscatter Diffraction maps show that the addition of both scandium and TiBor grain refiners were successful in controlling the microstructure of the melt pools for both alloys. The scandium additions resulted in a mixture of fine equiaxed grains and fine-to-moderately sized columnar grains, whereas TiBor additions resulted in fine homogenous and evenly distributed equiaxed grains. Despite the very high cooling rates the grain refinement principles for laser melting are the same as classical solidification. The results from this study can be used as a basis for further studies on developing customised alloys for Selective Laser Melting (SLM)