13,756 research outputs found

    Bouncing Eddington-inspired Born-Infeld cosmologies: an alternative to Inflation ?

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    We study the dynamics of a homogeneous and isotropic Friedmann-Robertson-Walker universe in the context of the Eddington-inspired Born-Infeld theory of gravity. We generalize earlier results, obtained in the context of a radiation dominated universe, to account for the evolution of a universe permeated by a perfect fluid with an arbitrary equation of state parameter ww. We show that a bounce may occur for κ>0\kappa >0, if ww is time-dependent, and we demonstrate that it is free from tensor singularities. We argue that Eddington-inspired Born-Infeld cosmologies may be a viable alternative to the inflationary paradigm as a solution to fundamental problems of the standard cosmological model.Comment: 4 pages, 1 figur

    Model-driven engineering techniques and tools for machine learning-enabled IoT applications: A scoping review

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    This paper reviews the literature on model-driven engineering (MDE) tools and languages for the internet of things (IoT). Due to the abundance of big data in the IoT, data analytics and machine learning (DAML) techniques play a key role in providing smart IoT applications. In particular, since a significant portion of the IoT data is sequential time series data, such as sensor data, time series analysis techniques are required. Therefore, IoT modeling languages and tools are expected to support DAML methods, including time series analysis techniques, out of the box. In this paper, we study and classify prior work in the literature through the mentioned lens and following the scoping review approach. Hence, the key underlying research questions are what MDE approaches, tools, and languages have been proposed and which ones have supported DAML techniques at the modeling level and in the scope of smart IoT services.info:eu-repo/semantics/publishedVersio

    Variabilidade espacial da distribuição da cobertura vegetal após colheita mecanizada da cana-de-açúcar.

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    O presente trabalho teve como objetivo avaliar a variabilidade espacial na distribuição da cobertura vegetal, no sistema de colheita mecanizada da cana-de-açúcar. O experimento foi conduzido na Fazenda Santa Clara, localizada em Lambari D?Oeste, MT, em uma área experimental de 9,75 ha, sob cultivo de cana-de-açúcar, demarcada em 70 pontos. Foram quantificadas a cobertura vegetal (kg.ha-1) e as brotações, as quais foram analisadas pela estatística descritiva e geoestatística. Os resultados mostraram que existe variabilidade espacial na distribuição da cobertura vegetal sobre o solo após a colheita mecanizada da cana-de-açúcar

    Exactly Solvable Interacting Spin-Ice Vertex Model

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    A special family of solvable five-vertex model is introduced on a square lattice. In addition to the usual nearest neighbor interactions, the vertices defining the model also interact alongone of the diagonals of the lattice. Such family of models includes in a special limit the standard six-vertex model. The exact solution of these models gives the first application of the matrix product ansatz introduced recently and applied successfully in the solution of quantum chains. The phase diagram and the free energy of the models are calculated in the thermodynamic limit. The models exhibit massless phases and our analyticaland numerical analysis indicate that such phases are governed by a conformal field theory with central charge c=1c=1 and continuosly varying critical exponents.Comment: 14 pages, 11 figure

    SBR performance for synthetic and fishery wastewater treatment

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    The evaluation of a SBR performance treating synthetic and fishery wastewater was performed. Without salt addition, COD and ammonia removal rates over than 50% were obtained, indicating the occurrence of the first nitrification step and COD removal. With 0.5% salt, removal rates lower than 60% were attained, for ammonia removal efficiency probably due to ionic strength changes and cellular plasmolysis leading to inactivation of the nitrification organisms. The SBR performance was greater for synthetic wastewater, due to the inherent and controlled characteristics. For both, lower SVI were achieved as a valuable indicator towards the assessment of the aggregated biomass structure.National Council of Scientific and Technological Development of Brazil (CNPq); BIEURAM III ALFA co-operation project (European Commission)

    Characterization of natural occurrence of Oenocarpus distichus in the state of Maranhão, Brazil.

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    In Maranhão States Amazon, bacaba stands out as an important resource to local populations. It is employed in human and animal feeding, building houses, traditional medicine and manufacturer goods. The economically viable part of this species is the processed pulp known as bacaba, sold in natura or frozen. Considering the great potential of sustainable economic exploitation of native fruit trees, such as the bacaba, occurrence areas of natural populations of O. distichus in three municipalities of the Gurupi micro region and two of the Chapada das Mangabeiras were mapped in order to subsidize future researches regarding conservation and use of the germplasm. Bacaba populations were mapped in cities of the two microregions: 1) Gurupi where soils, in general, are of low natural fertility with predominance of dystrophic plinthudults and red-yellow dystrophic and plinthic soils and; 2) Chapada das Mangabeiras, where yellow dystrophic hapludox soils are found; and in the escarpments the litholic dystrophic neosoils are common. In these micro regions, bacaba populations are reduced to individuals found in backyards

    Euler-Lagrange equations for composition functionals in calculus of variations on time scales

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    In this paper we consider the problem of the calculus of variations for a functional which is the composition of a certain scalar function HH with the delta integral of a vector valued field ff, i.e., of the form H(abf(t,xσ(t),xΔ(t))Δt)H(\int_{a}^{b}f(t,x^{\sigma}(t),x^{\Delta}(t))\Delta t). Euler-Lagrange equations, natural boundary conditions for such problems as well as a necessary optimality condition for isoperimetric problems, on a general time scale, are given. A number of corollaries are obtained, and several examples illustrating the new results are discussed in detail.Comment: Submitted 10-May-2009 to Discrete and Continuous Dynamical Systems (DCDS-B); revised 10-March-2010; accepted 04-July-201
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