2,585 research outputs found

    Phase coexistence and relaxation of the spherical frustrated Blume-Emery-Griffiths model with attractive particles coupling

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    We study the equilibrium and dynamical properties of a spherical version of the frustrated Blume-Emery-Griffiths model at mean field level for attractive particle-particle coupling (K>0). Beyond a second order transition line from a paramagnetic to a (replica symmetric) spin glass phase, the density-temperature phase diagram is characterized by a tricritical point from which, interestingly, a first order transition line starts with coexistence of the two phases. In the Langevin dynamics the paramagnetic/spin glass discontinuous transition line is found to be dependent on the initial density; close to this line, on the paramagnetic side, the correlation-response plot displays interrupted aging.Comment: to be published on Europhysics Letter

    Laser-aided Directed Metal Deposition of Ni-based superalloy powder

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    Abstract The subject of repairing Ni-based parts with state-of-the-art technologies is increasingly addressed both for research and industrial purposes, aiming to cost saving mainly in aerospace and automotive. In this frame, laser-aided Directed Metal Deposition (DMD) with injection of powder is investigated in this paper since minimal distortion of the work-piece, reduced heat-affected zones and better surface quality are benefited in comparison with conventional techniques. Actual application to overhaul Ni-based components is aimed, therefore homologous powder is fed by means of a 3-way feeding nozzle over the substrate; a disc laser is used as heat source. The chemical composition of both the substrate and the powder is preliminarily investigated via areal and punctual EDS inspections. A 2-factor, 2-level experimental plan is drawn to discuss the main effects of the processing variables laser power and processing speed. Namely, the resulting trends are given and compared with similar findings in the literature. Interestingly, dilution as a measure of metal affection is found to be lower than 25%, hence the operating window is deemed to be suitable for both repairing and fabrication of parts. Eventually, repairing by means of side overlapping and multi-level deposition traces on artificial square-shaped grooves is performed: indeed, similar slots are made before DMD to preliminarily remove any local imperfection upon improper casting of the part in the actual industrial process. Although a number of micropores are found, the process is deemed to comply with usual referred standards; in particular, a proper processing window has been found to prevent the occurrence of hot cracking which usually affects the compliance to stress

    2D and Quasi-2D Perovskites for Optoelectronic Devices

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    HYBRID ORCHESTRATION: The use of samples as integration to the acoustic recording in Maurizio Malagnini’s Music

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    Since 1983, the world of MIDI has developed to a point to redifine the entire process of creating music. Through the years this has led the client (such as a film director) to expect high quality mock-ups that give a true representation of the final work, while before that the composer used to play at the piano a minimal idea of a larger scale work. Convincing a client that spending the money about to be invested on the movie was worthy was a matter of trust, while nowadays technology has given the opportunity to the composer to fully prove his abilities. Having said that, technology has led to the issue that while in the analog era was enough to write the score to achieve a complicated orchestral arrangement, now the composer has to also be able in sequence it. This led to an impoverishment of film music, that sees less and less the advent of new composers like John Williams. But sample libraries and the sequencing process should not be seen as an obstacle: with the right tools the composer can still be able to produce fantastic music with no excessive efforts. Also, samples are a fantastic weapon in the hand of the composer to deliver a good product saving time and allowing him to use the budget the way he prefers with no need of having to record every single instrument included in the composition. In this thesis I will talk about all this factors as seen from the perspective of an acclaimed composer in the UK such as Maurizio Malagnini, whom I had the priviledge of studying with for many years. Most of the content of this thesis comes from an interview I had with him on April 29th 2016 in his house in London.https://remix.berklee.edu/graduate-studies-scoring/1053/thumbnail.jp

    Keep Working Hands on Working Land

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    Strategies for Effective Farmland Transitions, Succession Planning, and Landowner Educationhttps://scholarworks.umt.edu/grad_portfolios/1330/thumbnail.jp

    2D and Quasi-2D Perovskites for Optoelectronic Devices

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    The Onset of Convective Coupling and Freezing in the White Dwarfs of 47 Tucanae

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    Using images from the Hubble Space Telescope Advanced Camera for Surveys, we measure the rate of cooling of white dwarfs in the globular cluster 47 Tucanae and compare it to modelled cooling curves. We examine the effects of the outer convective envelope reaching the nearly isothermal degenerate core and the release of latent heat during core crystallisation on the white dwarf cooling rates. For white dwarfs typical of 47 Tuc, the onset of these effects occur at similar times. The latent heat released during crystallisation is a small heat source. In contrast, the heat reservoir of the degenerate core is substantially larger. When the convective envelope reaches the nearly isothermal interior of the white dwarf, the star becomes brighter than it would be in the absence of this effect. Our modelled cooling curves that include this convective coupling closely match the observed luminosity function of the white dwarfs in 47 Tuc.Comment: 6 pages, 5 figures. Submitted to MNRA
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