1,686 research outputs found

    A adoção do padrão internacional de relatórios financeiros em portugal: podem os custos esperados ser reduzidos?

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    In this paper we use a cost-benefit framework to discuss some of the expected effects related to the Portuguese adoption of the International Financial Reporting Standards (IFRS). Given the circumstances underlying this implementation, we anticipate that the overall net result following an analysis of costs and benefits will be negative. Therefore, we also examine what seems to be the causal factor behind this outcome and a potential way of reducing the net cost of adopting the IFRS. The costs are related to the professional updating of accounting skills of those directly or indirectly involved in the accounting process. A part of these costs will be incremental and permanent over time mainly due to the fact that two accounting systems will be kept in place. The adoption of a single accounting system, that based on the IFRS, would appear to be a possible solution to reduce such costs

    Domus tutor: A CBR tutoring agent for student support

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    The changes introduced by the Bologna process in the educational paradigm, moving from a lecturer centered paradigm to a learner centered paradigm, involves a more supported learning process based on learning outcomes and the adoption of new pedagogical methodologies. In this paper we present our strategy of integration of tutoring agents in learning environments, using the features of intelligent tutoring systems adapted to collaborative environments. The Domus Tutor agent is the face of the adaptive learning environment that integrates Learning Design, groupware and collaborative work technologies. The adaptation of the system to the learner profile is based on case-based reasoning methodology; witch is one of the major reasoning paradigms in artificial intelligence.- (undefined

    On the effect of contraction ratio in viscoelastic flow through abrupt contractions

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    A numerical study of the creeping flow of a PTT fluid through planar sudden contractions was carried out to quantify the effect of contraction ratio upon the flow characteristics (streamlines and size and intensity of recirculation vortices). The relevant governing equations were solved with a finite volume method embodying a new high-resolution scheme (Alves et al. [Int. J. Numer. Meth. Fluids 41 (2003) 47]) for the discretisation of convection terms, which is here explained and shown to yield improved accuracy and robustness. The results of the simulations, in terms of streamline patterns, give further evidence for a lip-vortex enhancement mechanism and are in remarkable agreement with flow visualization photographs from the literature. In addition, the results show that the variation of flow features in the vicinity of the re-entrant corner, such as lip vortex size and streamlines, are dominated by downstream quantities and scale with the common definition for the Deborah number in this flow, while flow characteristics in the salient corner region scale with that Deborah number divided by the contraction ratio

    Viscoelastic flow in a 3D square/square contraction: Visualizations and simulations.

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    The inertialess three-dimensional (3D) flow of viscoelastic shear-thinning fluids in a 4:1 sudden square-square contraction was investigated experimentally and numerically and compared with the flow of inelastic fluids. Whereas for a Newtonian fluid the vortex length remains unchanged at low Reynolds numbers, with the non-Newtonian fluid there is a large increase in vortex length with fluid elasticity leading to unstable periodic flow at higher flow rates. In the steady flow regime the vortices are 3D and fluid particles enter the vortex at the middle plane, rotate towards its eye, drift sideways to the corner-plane vortex, rotate to its periphery, and exit to the downstream duct. Such dynamic process is reverse of that observed and predicted with Newtonian fluids. Numerical predictions using a multimode Phan-Thien–Tanner viscoelastic model are found to match the visualizations accurately and in particular are able to replicate the observed flow reversal. The effect of fluid rheology on flow reversal, vortex enhancement, and entry pressure drop is investigated in detail

    Modelação estatística dos índices de sinistralidade, aplicados ao setor da construção

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    Face ao quadro problemático das estatísticas de sinistralidade e considerando a Segurança na construção uma missão vital e de primordial significado para a sociedade, pretendeu-se com o presente estudo desenvolver modelos matemáticos, com capacidade explicativa do comportamento dos índices de sinistralidade em função de variáveis setoriais e globais como a taxa de desemprego e a taxa de crescimento do PIB de Portugal. Foram utilizados dados oficiais relativos a uma amostra de conveniência composta por 58 empresas do setor da construção, referente ao período de 6 anos. Foi efetuado o tratamento estatístico dos dados e desenhados modelos com base em regressões lineares. No final, dois dos modelos desenvolvidos apresentaram capacidade explicativa. Sendo que nestes aparecem como variáveis relevantes, a taxa de desemprego e os custos de formação por trabalhador. Apesar da capacidade explicativa dos modelos e da possibilidade da sua utilização pelas empresas do setor, como ferramenta potenciadora da Prevenção dos acidentes ocupacionais, é ainda questionada a eventual falta de consistência dos dados e a qualidade da formação ministrada nas empresas

    REXIB: Remote Experiments Interface Builder

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    Remote Experimentation is an educational resource that allows teachers to strengthen the practical contents of science & engineering courses. However, building up the interfaces to remote experiments is not a trivial task. Although teachers normally master the practical contents addressed by a particular remote experiment they usually lack the programming skills required to quickly build up the corresponding web interface. This paper describes the automatic generation of experiment interfaces through a web-accessible Java application. The application displays a list of existent modules and once the requested modules have been selected, it generates the code that enables the browser to display the experiment interface. The tools main advantage is enabling non-tech teachers to create their own remote experiments

    Purely Elastic Flow Asymmetries

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    Using a numerical technique we demonstrate that the flow of the simplest differential viscoelastic fluid model (i.e., the upper-convected Maxwell model) goes through a bifurcation to a steady asymmetric state when flowing in a perfectly symmetric ‘‘cross-slot’’ geometry. We show that this asymmetry is purely elastic in nature and that the effect of inertia is a stabilizing one. Our results are in qualitative agreement with very recent experimental visualizations of a similar flow in the microfluidic apparatus of Arratia et al. [Phys. Rev. Lett. 96, 144502 (2006)]

    Uniform flow of viscoelastic fluids past a confined falling cylinder

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    Uniform steady flow of viscoelastic fluids past a cylinder placed between two moving parallel plates is investigated numerically with a finite-volume method. This configuration is equivalent to the steady settling of a cylinder in a viscoelastic fluid, and here, a 50% blockage ratio is considered. Five constitutive models are employed (UCM, Oldroyd-B, FENE-CR, PTT and Giesekus) to assess the effect of rheological properties on the flow kinematics and wake patterns. Simulations were carried out under creeping flow conditions, using very fine meshes, especially in the wake of the cylinder where large normal stresses are observed at high Deborah numbers. Some of the results are compared with numerical data from the literature, mainly in terms of a drag coefficient, and significant discrepancies are found, especially for the constant-viscosity constitutive models. Accurate solutions could be obtained up to maximum Deborah numbers clearly in excess of those reported in the literature, especially with the PTT and FENECR models. The existence or not of a negative wake is identified for each set of model parameters
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