2,460 research outputs found

    El saber callar a tiempo en Ernesto Cardenal y en la poesía campesina de Solentiname

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    Brentano’s lectures on positivism (1893-1894) and his relationship to Ernst Mach

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    This paper is mainly about Brentano’s commentaries on Ernst Mach in his lectures “Contemporary philosophical questions” which he held one year before he left Austria. I will first identify the main sources of Brentano’s interests in Comte’s and J. S. Mill’s positivism during his Würzburg period. The second section provides a short overview of Brentano’s 1893-1894 lectures and his criticism of Comte, Kirchhoff, and Mill. The next sections bear on Brentano’s criticism of Mach’s monism and Brentano’s argument against the reduction of the mental based on his theory of intentionality. The last section is about Brentano’s proposal to replace the identity relation in Mach’s theory of elements by that of intentional correlation. I conclude with a remark on the history of philosophy in Austria

    Entorn de la unitat del "Llibre d'Amic e Amat"

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    Regular or random: a discussion on SPH initial particle distribution

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    Smoothed Particle Hydrodynamics (SPH) has been used to model a variety of objects and for a number of applications in engineering and science. These have ranged from astrophysicstofluidandsolidmechanicsproblems. Muchresearchhasbeendedicatedtoforming a better understanding of the SPH method. As a consequence, new numerical techniques have been developed in order to overcome some of its difficulties and limitations. Nonetheless, there is still a gap in information concerning the impact of the initial particle distribution on the effectiveness of the SPH method. With this in mind, a review of existing recommendations for SPH initial configurations has been conducted in this paper. In addition to this, a numerical exampleispresentedwhichisbasedontheclassical2-Dliddrivencavityproblem,whereinthe upperboundaryexertsahorizontalshearforceonthefluidinsidethecavity. Thevelocityofthe lid is v = 10−3 m/s and the cavity is square with length l = 1x10−3 m. The fluid was modelled with a density ρ = 1000 kg/m3, a viscosity µ = 10−3 kg/ms) (Re = 1). These parameters were held constant for all consequent comparisons. The number of particles is varied from (20 × 20) to (80 × 80). The initial distribution is modelled in three different ways: (i) regular, (ii) pseudo-random (with a 30% random deviation from the regular grid) and (iii) fully random. Theeffectivenessofeachinitialparticledistributionisassessedaccordingtothefieldvelocities and horizontal and vertical centreline velocity profiles. The impact of the initial particle distribution is highlighted and compared against a reference CFD result, and recommendations and conclusions are drawn for the SPH method

    3D multiphysics model for the simulation of electrochemical machining of stainless steel (SS316)

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    In Electrochemical Machining (ECM) - a method that uses anodic dissolution to remove metal - it is extremely difficult to predict material removal and resulting surface finish due to the complex interaction between the numerous parameters available in the machining conditions. In this paper, it is argued that a 3D coupled multiphysics finite element model is a suitable way to further develop the ability to model the ECM process. This builds on the work of previous researchers and further claims that the over-potential available at the surface of the workpiece is a crucial factor in ensuring satisfactory results. As a validation example, a real world problem for polishing via ECM of SS316 pipes is modelled and compared to empirical tests. Various physical and chemical effects, including those due to electrodynamics, fluid dynamic, and thermal and electrochemical phenomena were incorporated in the 3D geometric model of the proposed tool, workpiece and electrolyte. Predictions were made for current density, conductivity, fluid velocity, temperature, and crucially, with estimates of the deviations in over-potential. Results revealed a good agreement between simulation and experiment and these were sufficient to solve the immediate real problem presented but also to ensure that future additions to the technique could in the longer term lead to a better means of understanding a most useful manufacturing process

    Low X-Ray Luminosity Galaxy Clusters: Main goals, sample selection, photometric and spectroscopic observations

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    We present the study of nineteen low X-ray luminosity galaxy clusters (LX_X \sim 0.5--45 ×\times 104310^{43} erg s1^{-1}), selected from the ROSAT Position Sensitive Proportional Counters (PSPC) Pointed Observations (Vikhlinin et al. 1998) and the revised version of Mullis et al. (2003) in the redshift range of 0.16 to 0.7. This is the introductory paper of a series presenting the sample selection, photometric and spectroscopic observations and data reduction. Photometric data in different passbands were taken for eight galaxy clusters at Las Campanas Observatory; three clusters at Cerro Tololo Interamerican Observatory; and eight clusters at the Gemini Observatory. Spectroscopic data were collected for only four galaxy clusters using Gemini telescopes. With the photometry, the galaxies were defined based on the star-galaxy separation taking into account photometric parameters. For each galaxy cluster, the catalogues contain the PSF and aperture magnitudes of galaxies within the 90\% completeness limit. They are used together with structural parameters to study the galaxy morphology and to estimate photometric redshifts. With the spectroscopy, the derived galaxy velocity dispersion of our clusters ranged from 507 km~s1^{-1} for [VMF98]022 to 775 km~s1^{-1} for [VMF98]097 with signs of substructure. Cluster membership has been extensively discussed taking into account spectroscopic and photometric redshift estimates. In this sense, members are the galaxies within a projected radius of 0.75 Mpc from the X-ray mission peak and with cluster centric velocities smaller than the cluster velocity dispersion or 6000 km~s1^{-1}, respectively. These results will be used in forthcoming papers to study, among the main topics, the red cluster sequence, blue cloud and green populations; the galaxy luminosity function and cluster dynamics.Comment: 13 pages, 6 tables, 9 figures. Uses emulateapj. Accepted for publication in The Astronomical Journal. Some formatting errors fixe

    A new classification and linear sequence of extant gymnosperms

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    A new classification and linear sequence of the gymnosperms based on previous molecular and morphological phylogenetic and other studies is presented. Currently accepted genera are listed for each family and arranged according to their (probable) phylogenetic position. A full synonymy is provided, and types are listed for accepted genera. An index to genera assists in easy access to synonymy and family placement of genera.Peer reviewe
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