10,446 research outputs found

    Biodiversidade e melhoramento participativo: razão e prática Em busca de alternativas de caráter agronômico, nutricional, funcional e econômico.

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    The role of dissipation in biasing the vacuum selection in quantum field theory at finite temperature

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    We study the symmetry breaking pattern of an O(4) symmetric model of scalar fields, with both charged and neutral fields, interacting with a photon bath. Nagasawa and Brandenberger argued that in favourable circumstances the vacuum manifold would be reduced from S^3 to S^1. Here it is shown that a selective condensation of the neutral fields, that are not directly coupled to photons, can be achieved in the presence of a minimal ``external'' dissipation, i.e. not related to interactions with a bath. This should be relevant in the early universe or in heavy-ion collisions where dissipation occurs due to expansion.Comment: Final version to appear in Phys. Rev. D, 2 figures added, 2 new sub-section

    Structural health monitoring of different geometry structures with optical fiber sensors

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    In this paper, we describe the structural health monitoring of several structures, with different geometry, materials and behaviors, using optical fiber sensors. Those studies aimed to demonstrate the feasibility of such technologies in structural health monitoring, with all the advantages inherent to the optical fiber technology

    Finite element modelling and analysis of crack shape evolution in mode-I fatigue Middle Cracked Tension specimens

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    A numerical procedure was employed to study the shape evolution of fatigue cracks in Middle Cracked Tension specimens. This iterative procedure consists of a 3D finite element analysis to obtain the displacement field in the cracked body, calculation of stress intensity factors along crack front and definition of local crack advances considering the Paris law. Numerical predictions were compared with experimental crack shapes with a good agreement. The evolution of crack shape was analysed for different propagation conditions considering robust dependent parameters. Two main propagation stages were identified: an initial transient stage highly dependent on initial crack shape and a stable stage where the crack follows preferred paths. Mathematical models were proposed for transient and stable stages consisting of exponential and polynomial functions, respectively. The transition between both stages was defined considering two criteria: the rate of shape variation and the distance to stable shape. Finally, the crack shape change was linked with the distribution of stress intensity factor along crack front.http://www.sciencedirect.com/science/article/B6V2R-4RGFD3P-1/1/e08212c92d2476b00aceb521ee4e521

    A geochemical modeling approach in Lardosa region (Castelo Branco): an environmental management tool

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    Comunicação oral da qual só está disponível o resumo.A geochemical modeling approach in Lardosa region (Castelo Branco): an environmental management tool

    Assessment of the traffic noise on thin layers

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    Traffic noise is an important branch of the environment pollution which deeply affects the population and for that reason it has been included in the set of pavement performance indicators. Nevertheless, the knowledge on the environmental impact of the existing surface pavement layers is very limited, particularly for what respects to tyre/road noise of thin layers. These layers are at the present time widely used in a great extent with rubberized asphalt both in urban and rural roads especially in the north of Portugal due to environmental concerns. In this paper the comparison of the tyre/road noise (Lmax) generated in roads with thin surface layers is made. The noise levels generated by light and heavy vehicles are set according to the Statistical Pass-By Method (SPB) of which test methods is described in the standard ISO 11819-1:1997. At management level the information provided by tyre/road noise tests is essential to support environmentally sustainable construction and maintenance alternatives. Furthermore, at project level, the results give some insight about the relation surface layers/traffic composition

    NOSTROMO - D5.1 - ATM Performance Metamodels - Preliminary Release

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    This deliverable presents the results obtained with the meta-modelling process presented in D3.1 and D3.2 applied to the two micromodels (or simulators), Mercury and FLITAN, themselves implementing concepts from four SESAR solutions, PJ01.01, PJ07.02, PJ08-01, and PJ02.08. The objective of the meta-modelling process is explained briefly again in the introduction, in particular with respect to performance assessment. The rationale for the selection of the SESAR solutions implemented in the simulators are briefly explained too. The simulators are presented in two distinct chapters. First, a general presentation of each simulator is given, with past challenges and development, before explaining the development steps carried out to implement the concepts from the chosen solutions. Domain research questions that could be answered by these implementations are highlighted along the way. The meta-modelling process is then briefly explained again, followed by the results obtained with the two simulators, in distinct sections. The results highlight the performance of the meta-model with respect to approximating the output of the micromodels, but not the performance of the models themselves with respect to the research questions, which will be explored in WP7 instead. The deliverable closes with some considerations on the meta-modelling performance and next steps for this line of work

    Towards a digitally fabricated disassemble-able building system: a CNC fabricated T-Slot joint

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    Growing dissemination of digital fabrication technologies coupled with a renewed interest in wood as a construction material have led to a resurgence of research into integral wood joints. Recent research on digitally fabricated wood joints has focused primarily on robotic or on CNC router produced snap-fit or tab-and-slot joints. These types of joints have several problems in sheathing to structure connections. The present paper reports on research into design and fabrication of T-slot joints that allow hidden back-face connections which are disassemble-able. It is part of an ongoing research whose aim is to develop disassemble-able and mass customizable construction system of partition walls for building renovation.info:eu-repo/semantics/publishedVersio

    Back to Dakar: Decolonizing international political economy through dependency theory

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    Whereas the field of International Political Economy (IPE) included a diversity of voices at its outset, histories of the field tend to marginalize certain contributions - particularly those from the Global South. The endeavor to decolonize IPE offers an opportunity to look back at IPE’s history, re-discover the marginalized voices, and imagine new possible futures. This article engages with contemporary calls to decolonize IPE and proposes an alternative route to do so by recovering dependency theory. We argue that dependency theory can be conceptualized as a peripheral IPE perspective that was committed to thinking from the Global South and to producing politically engaged scholarship just as the field was being formed. The article elaborates on the key tenets of dependency theory, contrasting it with mainstream IPE, and putting it in dialogue with decolonial approaches. To demonstrate the simultaneous non-Eurocentric, anti-colonial, and policy-oriented potential of dependency theory, we recover a foundational moment that disciplinary histories of IPE have forgotten: the 1972 Dakar conference, organized by Samir Amin, with the participation of leading Latin American and African dependency scholars
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