2,987 research outputs found

    Critical exponents for the long-range Ising chain using a transfer matrix approach

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    The critical behavior of the Ising chain with long-range ferromagnetic interactions decaying with distance rαr^\alpha, 1<α<21<\alpha<2, is investigated using a numerically efficient transfer matrix (TM) method. Finite size approximations to the infinite chain are considered, in which both the number of spins and the number of interaction constants can be independently increased. Systems with interactions between spins up to 18 sites apart and up to 2500 spins in the chain are considered. We obtain data for the critical exponents ν\nu associated with the correlation length based on the Finite Range Scaling (FRS) hypothesis. FRS expressions require the evaluation of derivatives of the thermodynamical properties, which are obtained with the help of analytical recurrence expressions obtained within the TM framework. The Van den Broeck extrapolation procedure is applied in order to estimate the convergence of the exponents. The TM procedure reduces the dimension of the matrices and circumvents several numerical matrix operations.Comment: 10 pages, 2 figures, Conference NEXT Sigma Ph

    Ethics in Authorship: Considerations and Concerns

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    A new approach on the stability analysis in ELKO cosmology

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    In this work it has been developed a new approach to study the stability of a system composed by an ELKO field interacting with dark matter, which could give some contribution in order to alleviate the cosmic coincidence problem. It is assumed that the potential which characterizes the ELKO field is not specified, but it is related to a constant parameter δ\delta. The strength of the interaction between matter and ELKO field is characterized by a constant parameter β\beta and it is also assumed that both ELKO field as matter energy density are related to their pressures by equations of state parameters ωϕ\omega_\phi and ωm\omega_m, respectively. The system of equations is analysed by a dynamical system approach. It has been found the conditions of stability between the parameters δ\delta and β\beta in order to have stable fixed points for the system for different values of the equation of state parameters ωϕ\omega_\phi and ωm\omega_m, and the results are presented in form of tables. The possibility of decay of ELKO field into dark matter or vice versa can be read directly from the tables, since the parameters δ\delta and β\beta satisfy some inequalities. It allows us to constrain the potential assuming that we have a stable system for different interactions terms between the ELKO field and dark matter. The cosmic coincidence problem can be alleviated for some specific relations between the parameters of the model.Comment: 16 pages, some new comments in the Introduction and at the begining of Section I

    Framework for the collection of good practices regarding the welcoming and integration of refugees and migrants

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    The present document is the framework of one specificactivity of the PandPAS projectPre and Post-Arrival Schemes to facilitate inclusion and prevent xenophobia and radicalization. The framework has been drafted by CIES, ISCTE-IUL, with the goal of supporting the collection and analysis of good practices regarding refugees welcoming and integrationbyall partners of the PandPAS procect.The PandPASproject focuses onpost-arrival support for the integration of asylum seekers, and migrants.Itaims at producing tools for pre departure activities and pilot experiences for the social inclusion and active participation of migrants in hosting territories.Thisdocument starts with the description of the project activityin which the collection was carried out. It continues with the definition of a good practice andthe criteria to choose a good practice regarding the welcoming and integration of refugees and migrants. The process of collecting the good practices is also described. In the last section of the document is provided the template to fill-in regardingeach good practice.info:eu-repo/semantics/publishedVersio

    Realising damage-tolerant nacre-inspired CFRP

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    Inthiswork,anacre-inspiredCarbonFibreReinforcedPolymer(CFRP)compositeis designed,synthesisedandtested. Analyticalandnumericalmodelsareusedtodesign a tiled micro-structure, mimicking the staggered arrangement of ceramic platelets in nacreandexploitinggeometricalinterlocksforcrackdeflectionanddamagediffusion. The designed pattern of tiles is then laser-engraved in the laminate plies. In order to increase the damage-spreading capability of the material, a thin layer of poly(lactic acid) (PLA) is film-cast on the interlaminar region, both as a continuous film and as a pattern of fractal-shaped patches. Three-point bending tests show how the nacre-like micro-structure succeeds in deflecting cracks, with damage diffusion being significantly improved by the addition of PLA at the interface between tiles. It is observed that a texture of discontinuous fractal-shaped PLA patches can increase damage diffusion, by promoting the unlocking of tiles whilst preserving the interface strength

    Microtopographic Inspection of Thermoplastic Rubber Shoe’s Sole: The Influence of Surface Roughness on Sole to Leather Gluing

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    In Portugal quality shoe’s industry has a major economical importance. The strength and quality of the gluing of the sole to leather are of major importance in the process of making a high quality shoe. This pasting process is standardized for different kinds of sole/leather combinations. However even if proceeding carefully, strictly by the rules, problems due happen and specially as new kinds of sole’s materials and leather’ types are introduced in the production lines. A careful physical characterization of the gluing process as well as all items intervening is again necessary

    Risk management of bored piling construction on sandy soils with real-time cost control

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    UIDP/GEO/04035/2020In a global society, in which geotechnical projects are increasingly designed in a country other than the one where construction takes place, geotechnical risk management must be extended to cover infrastructure works, which are smaller than dams and tunnels, for example, since there is a significant impact on works budget imponderables. Therefore, a risk management methodology based on the likelihood of the occurrence of certain events and their economic consequences is proposed, which is applicable to bored piles (Kelly drilled) in coarse soils, easy to use, and simple to implement since the initial stage of construction. Of 12 case studies of construction works involving bored piles (Kelly drilled) carried out in Luanda (Angola), two selected examples involving the proposed risk methodology on sandy soil layers with interbedded clays are discussed. Subsequently, whether the overall foundation contract budget is affected by assessed risk is determined, and what influence it has on the budget in the light of mitigating factors and associated real costs. This method intended to encourage the adaptation of sustainable risk management in bored piles construction by the site project managers, involving risk analysis concurrently with budgetary review. Though the level of assessed technical risk may be acceptable, overall costs associated with the contract in question may not be acceptable.publishersversionpublishe

    On the applicability of transfer function models for ssi embedment effects

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    Soil-structure interaction (SSI) effects are typically neglected for relatively lightweight buildings that are less than two-three storeys high with a limited footprint area and resting on shallow foundations (i.e., not featuring a basement). However, when the above conditions are not satisfied, and in particular when large basements are present, important kinematic SSI may develop, causing the foundation-level motion to deviate from the free-field one due to embedment effects. In the literature, transfer function models that estimate the filtering effect induced by rigid massless embedded foundations are available to “transform” foundation-level recordings into free-field ones, and vice-versa. This work describes therefore a numerical study aimed at assessing potential limits of the applicability of such transfer functions through the employment of a 3D nonlinear soil-block model representing a layered soil, recently developed and validated by the authors, and featuring on top a large heavy building with basement. A number of finite element site response analyses were carried out for different seismic input signals, soil profiles and embedment depths of the building’s basement. The numerically obtained transfer functions were compared with the curves derived using two analytical models. It was observed that the latter are able to reliably predict the embedment effects in “idealised” soil/input conditions under which they have been developed. However, in real conditions, namely when a non-homogeneous profile with nonlinear behaviour under a given seismic excitation is considered, especially in presence of a basement that is more than one storey high, they may fail in capturing some features, such as the frequency-dependent amplification of the motion at the basement level of a building with respect to the free-field one
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