6,043 research outputs found

    Computer simulation of the microstructure and rheology of semi-solid alloys under shear

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    The rheological behavior of metallic alloys containing both solid and liquid phases is investigated in the low solid fraction range (<50%). This behavior depends on both the solid fraction and the shear rate. The concept of Effective Volume Fraction (EVF) is used to decorrelate the influence of these two parameters. At high shear rate the slurry behaves like a suspension of hard spheres, whereas at lower shear rate, particles tend to aggregate in clusters, entrapping liquid and thus, increasing the EVF and the viscosity. A lattice model is introduced to simulate the aggregation / break-up processes within a slurry under shear. When the steady state is reached, the entrapped liquid fraction is calculated, leading to a viscosity estimation. Simulation results for the viscosity and 3D cluster structure are in good agreement with experimental results.Comment: 30 pages, 17 figures, to be published in Acta Mate

    Colours and aircraft interiors. Design scenarios for a regional aircraft cabin.

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    The paper aims to investigate the use of colour and its perception within the cabin of a regional aircraft used for short distances and it is divided into two parts. The first part presents an analysis of the literature and the state of the art on the use of colour both within the aeronautical sector and in comparable sectors, such as that of interior architecture, where over the last few decades researchers formulated different theories of approach. The case studies examined show that, today, the choice of using colour is mainly based on marketing factors linked to the corporate branding of airlines, with a lack of sensitivity to human factors. The literature on colour, on the other hand, suggests that the different tones of colour have a strong impact from a physiological and psychological point of view, factors that must be taken into consideration to improve the experience of wellbeing on board, defining a framework of requirements. The chromatic hypotheses were, then, examined and compared through a preliminary perceptual test conducted on a sample of 20 subjects aimed at evaluating and defining guidelines for approaching the colour project. The objective of the guidelines is the construction of chromatic design scenarios defining a comfortable environment from the visual point of view and capable not only of generating a pleasant, comfortable travel experience but also a feeling of security and limiting the typical unwanted perceptions related to flight. The paper is part of the dissemination of the H2020 CASTLE project (CAbin Systems design Toward passenger welLbEing)

    The extended comfort. Analysing the flight journey through a design-oriented approach.

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    The study of passengers' comfort on an aircraft is a research field that, has been able to accommodate both quantitative contributions, deriving from disciplines such as ergonomics, and qualitative contributions coming from product design. In recent years, design research has also focused on experiential and perceptive aspects, considering disciplines such as Interaction Design and User Experience. In the first instance, the paper aims to systemize the different design-oriented approaches that generated a complex map based also on the support of visual narration. In the map the flight experience is treated as if it were a service, analysing the entire customer journey to highlight the most critical issues. The methodological steps, based on the analysis of the activities, as well as those based on the optimization of the components, are then integrated into a holistic vision. The system has been created on the basis of case studies drawn from aircraft currently in service and from still embryonic concepts, capable of providing useful categories of analysis. The paper ends with the application of the map to an application study case: the CASTLE project (CAbin Systems design Toward passenger welLbEing)

    Lymphocyte Subsets and Inflammatory Cytokines of Monoclonal Gammopathy of Undetermined Significance and Multiple Myeloma

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    Almost all multiple myeloma (MM) cases have been demonstrated to be linked to earlier monoclonal gammopathy of undetermined significance (MGUS). Nevertheless, there are no identified characteristics in the diagnosis of MGUS that have been helpful in differentiating subjects whose cancer may progress to a malignant situation. Regarding malignancy, the role of lymphocyte subsets and cytokines at the beginning of neoplastic diseases is now incontestable. In this review, we have concentrated our attention on the equilibrium between the diverse lymphocyte subsets and the cytokine system and summarized the current state of knowledge, providing an overview of the condition of the entire system in MGUS and MM. In an age where the therapy of neoplastic monoclonal gammopathies largely relies on drugs capable of acting on the immune system (immunomodulants, immunological checkpoint inhibitors, CAR-T), detailed knowledge of the the differences existing in benign and neoplastic forms of gammopathy is the main foundation for the adequate and optimal use of new drugs

    Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808

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    We report on the discovery of coherent pulsations at a period of 2.9 ms from the X-ray transient MAXI J0911-655 in the globular cluster NGC 2808. We observed X-ray pulsations at a frequency of ∼339.97\sim339.97 Hz in three different observations of the source performed with XMM-Newton and NuSTAR during the source outburst. This newly discovered accreting millisecond pulsar is part of an ultra-compact binary system characterised by an orbital period of 44.344.3 minutes and a projected semi-major axis of ∼17.6\sim17.6 lt-ms. Based on the mass function we estimate a minimum companion mass of 0.024 M⊙_{\odot}, which assumes a neutron star mass of 1.4 M⊙_{\odot} and a maximum inclination angle of 75∘75^{\circ} (derived from the lack of eclipses and dips in the light-curve of the source). We find that the companion star's Roche-Lobe could either be filled by a hot (5×1065\times 10^{6} K) pure helium white dwarf with a 0.028 M⊙_{\odot} mass (implying i≃58∘i\simeq58^{\circ}) or an old (>5 Gyr) brown dwarf with metallicity abundances between solar/sub-solar and mass ranging in the interval 0.065−-0.085 M⊙_{\odot} (16 < ii < 21). During the outburst the broad-band energy spectra are well described by a superposition of a weak black-body component (kT∼\sim 0.5 keV) and a hard cutoff power-law with photon index Γ∼\Gamma \sim 1.7 and cut-off at a temperature kTe∼_e\sim 130 keV. Up to the latest Swift-XRT observation performed on 2016 July 19 the source has been observed in outburst for almost 150 days, which makes MAXI J0911-655 the second accreting millisecond X-ray pulsar with outburst duration longer than 100 days.Comment: 7 pages, 5 figures, accepted for publication in A&

    Interpreting physical performance in professional soccer match-play: Should we be more pragmatic in our approach?

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    Academic and practitioner interest in the physical performance of male professional soccer players in the competition setting determined via time-motion analyses has grown substantially over the last four decades leading to a substantial body of published research and aiding development of a more systematic evidence-based framework for physical conditioning. Findings have forcibly shaped contemporary opinions in the sport with researchers and practitioners frequently emphasising the important role that physical performance plays in match outcomes. Time-motion analyses have also influenced practice as player conditioning programmes can be tailored according to the different physical demands identified across individual playing positions. Yet despite a more systematic approach to physical conditioning, data indicate that even at the very highest standards of competition, the contemporary player is still susceptible to transient and end-game fatigue. Over the course of this article, the author suggests that a more pragmatic approach to interpreting the current body of time-motion analysis data and its application in the practical setting is nevertheless required. Examples of this are addressed using findings in the literature to examine: a) the association between competitive physical performance and ‘success’ in professional soccer, b) current approaches to interpreting differences in time-motion analysis data across playing positions and, c) whether data can realistically be used to demonstrate the occurrence of fatigue in match-play. Gaps in the current literature and directions for future research are also identified
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