967 resultados para CURVED BOUNDARIES


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The aim of this work is to present a formulation of the boundary element method to analyse elastic and isotropic plates with curved boundaries. In this study the plate boundary is approximated, along each element, by a second degree polynomial relation or by a circular arch, in order to better represent the real boundary. The numerical integration is performed by the self-adaptive coordinate transformation proposed by Telles. The effective shear forces are approximated by concentrated reactions applied at the boundary element nodes, according to the alternative formulation introduced by Paiva. Some examples are presented to demonstrate the better accuracy obtained with the proposed elements.

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We propose a discontinuous-Galerkin-based immersed boundary method for elasticity problems. The resulting numerical scheme does not require boundary fitting meshes and avoids boundary locking by switching the elements intersected by the boundary to a discontinuous Galerkin approximation. Special emphasis is placed on the construction of a method that retains an optimal convergence rate in the presence of non-homogeneous essential and natural boundary conditions. The role of each one of the approximations introduced is illustrated by analyzing an analog problem in one spatial dimension. Finally, extensive two- and three-dimensional numerical experiments on linear and nonlinear elasticity problems verify that the proposed method leads to optimal convergence rates under combinations of essential and natural boundary conditions. (C) 2009 Elsevier B.V. All rights reserved.

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Depending on the temperature and the magnitude and orientation of an external magnetic field, the critical current density, J c , of a coated conductor can be limited either by the properties of the grain boundaries or by those of the grains. In order to ascertain what governs J c under different conditions, we have measured straight and curved tracks, patterned into RABiTS-MOD samples, while a magnetic field was swept in the plane of the films. Significantly different results were obtained at different field and temperature ranges, which we were able to attribute to J c being limited by either grain boundaries or grains.

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A model of laminar visual cortical dynamics proposes how 3D boundary and surface representations of slated and curved 3D objects and 2D images arise. The 3D boundary representations emerge from interactions between non-classical horizontal receptive field interactions with intracorticcal and intercortical feedback circuits. Such non-classical interactions contextually disambiguate classical receptive field responses to ambiguous visual cues using cells that are sensitive to angles and disparity gradients with cortical areas V1 and V2. These cells are all variants of bipole grouping cells. Model simulations show how horizontal connections can develop selectively to angles, how slanted surfaces can activate 3D boundary representations that are sensitive to angles and disparity gradients, how 3D filling-in occurs across slanted surfaces, how a 2D Necker cube image can be represented in 3D, and how bistable Necker cuber percepts occur. The model also explains data about slant aftereffects and 3D neon color spreading. It shows how habituative transmitters that help to control developement also help to trigger bistable 3D percepts and slant aftereffects, and how attention can influence which of these percepts is perceived by propogating along some object boundaries.

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This set of papers in this issue of "Addictive Behaviors" was presented at the 2004 'Addictions' conference, which, for the first time, was held in the Southern Hemisphere, on the Sunshine Coast of Queensland, Australia. The theme of the conference, Crossing Boundaries: Implications of Advances in Basic Sciences for the Management of Addiction, speaks for itself. The papers derive from a wide range of empirical paradigms and cover issues with relevance to the development of addiction, to the maintenance of problematic use, and to assessment, treatment, and relapse. Research from Europe and the United States is represented, as well as work from Australia. An international perspective is strongly emphasized from the initial paper by Obot, Poznyak, and Moneiro, (see record 2004-19599-015) which describes the WHO Report on the Neuroscience of Psychoactive Substance Use and Dependence, and summarises some of the report's implications for policy and practice. Hall, Carter, and Morley (see record 2004-19599-014) close the issue with a paper on the wide-ranging ethical implications of advances in neuroscience research, including issues arising from the identification of high risk for addiction, the potential for coercive pharmacotherapy, use of medications to enhance function, and risks to privacy.

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The Preamble1 was the initial legislative statement of matters construed by government to constitute charitable purposes in a common law context. It provided an outline of what was to become the core agenda for government’s relationship with charity. The resulting implied partnership, as viewed by government, endured for four centuries and in many different cultural contexts across the common law world. During that period, judicial mediation on the balance to be struck between government interest in acquiring value for granting tax exempt privileges and the right of individuals to freely dispose of property in accordance with their particular altruistic wishes steadily broadened the range of purposes deemed to be charitable, the vagaries of donor choice often prevailing over government interest in acquiring value for tax exemption.

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This paper argues a model of open system design for sustainable architecture, based on a thermodynamics framework of entropy as an evolutionary paradigm. The framework can be simplified to stating that an open system evolves in a non-linear pattern from a far-from-equilibrium state towards a non-equilibrium state of entropy balance, which is a highly ordered organization of the system when order comes out of chaos. This paper is work in progress on a PhD research project which aims to propose building information modelling for optimization and adaptation of buildings environmental performance as an alternative sustainable design program in architecture. It will be used for efficient distribution and consumption of energy and material resource in life-cycle buildings, with the active involvement of the end-users and the physical constraints of the natural environment.