57,037 research outputs found

    Reconfiguring the borderlands of identity: Preparing social justice educators

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    This article offers multiple pedagogical approaches for mobilizing Gloria AnzaldĂșa\u27s metaphor of borderlands to prepare social justice educators to address issues of justice and equity in increasingly diverse classroom settings. It describes an experiential course in multicultural education, including innovative processes through which Education students analyze the borderlands of identity, society, and geography through critical self-analysis, fieldwork, and social action. By investigating the intersectionality of social justice issues and the social construction of identity, students attempt to transform the borders of their own identities and engage in action projects to begin a process of bridging the edges of cultural inequity

    An unfitted Nitsche method for incompressible fluid-structure interaction using overlapping meshes

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    We consider the extension of the Nitsche method to the case of fluid–structure interaction problems on unfitted meshes. We give a stability analysis for the space semi-discretized problem and show how this estimate may be used to derive optimal error estimates for smooth solutions,irrespectively of the mesh/interface intersection. We also discuss different strategies for the time discretization, using either fully implicit or explicit coupling (loosely coupled) schemes. Some numerical examples illustrate the theoretical discussion

    Interpolation of bilinear operators and compactness

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    The behavior of bilinear operators acting on interpolation of Banach spaces for the ρ\rho method in relation to the compactness is analyzed. Similar results of Lions-Peetre, Hayakawa and Person's compactness theorems are obtained for the bilinear case and the ρ\rho method.Comment: This work was published at "Nonlinear Analysis: Theory, Methods and Applications, Volume 73, Issue 2, 2010, Pages 526-537". Since there are some gaps in the original proof of Theorem 4.3, Here we give a new proof. For this, we change the Lemma 4.

    N=2 SUGRA BPS Multi-center solutions, quadratic prepotentials and Freudenthal transformations

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    We present a detailed description of N=2 stationary BPS multicenter black hole solutions for quadratic prepotentials with an arbitrary number of centers and scalar fields making a systematic use of the algebraic properties of the matrix of second derivatives of the prepotential, S\mathcal{S}, which in this case is a scalar-independent matrix. In particular we obtain bounds on the physical parameter of the multicenter solution such as horizon areas and ADM mass. We discuss the possibility and convenience of setting up a basis of the symplectic vector space built from charge eigenvectors of the \ssigma, the set of vectors (\Ppm q_a) with \Ppm \ssigma-eigenspace proyectors. The anti-involution matrix S\mathcal{S} can be understood as a Freudenthal duality \tilde{x}=\ssigma x. We show that this duality can be generalized to "Freudenthal transformations" x\to \lambda\exp(\theta \ssigma) x= a x+b\tilde{x} under which the horizon area, ADM mass and intercenter distances scale up leaving constant the fix point scalars. In the special case λ=1\lambda=1, "\ssigma-rotations", the transformations leave invariant the solution. The standard Freudental duality can be written as \tilde x= \exp(\pi/2 \ssigma) x . We argue that these generalized transformations leave also invariant the general stringy extremal quartic form Δ4\Delta_4, Δ4(x)=Δ4(cos⁥Ξx+sin⁥Ξx~)\Delta_4(x)= \Delta_4(\cos\theta x+\sin\theta\tilde{x}).Comment: Latex 27 pages (11pt). Some modifications introduced. Minor misprints corrected. References adde

    A Generalized Method for Automatic Downhand and Wirefeed Control of a Welding Robot and Positioner

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    A generalized method for controlling a six degree-of-freedom (DOF) robot and a two DOF positioner used for arc welding operations is described. The welding path is defined in the part reference frame, and robot/positioner joint angles of the equivalent eight DOF serial linkage are determined via an iterative solution. Three algorithms are presented: the first solution controls motion of the eight DOF mechanism such that proper torch motion is achieved while minimizing the sum-of-squares of joint displacements; the second algorithm adds two constraint equations to achieve torch control while maintaining part orientation so that welding occurs in the downhand position; and the third algorithm adds the ability to control the proper orientation of a wire feed mechanism used in gas tungsten arc (GTA) welding operations. A verification of these algorithms is given using ROBOSIM, a NASA developed computer graphic simulation software package design for robot systems development

    Multiple path prediction for traffic scenes using LSTMs and mixture density models

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    This work presents an analysis of predicting multiple future paths of moving objects in traffic scenes by leveraging Long Short-Term Memory architectures (LSTMs) and Mixture Density Networks (MDNs) in a single-shot manner. Path prediction allows estimating the future positions of objects. This is useful in important applications such as security monitoring systems, Autonomous Driver Assistance Systems and assistive technologies. Normal approaches use observed positions (tracklets) of objects in video frames to predict their future paths as a sequence of position values. This can be treated as a time series. LSTMs have achieved good performance when dealing with time series. However, LSTMs have the limitation of only predicting a single path per tracklet. Path prediction is not a deterministic task and requires predicting with a level of uncertainty. Predicting multiple paths instead of a single one is therefore a more realistic manner of approaching this task. In this work, predicting a set of future paths with associated uncertainty was archived by combining LSTMs and MDNs. The evaluation was made on the KITTI and the CityFlow datasets on three type of objects, four prediction horizons and two different points of view (image coordinates and birds-eye vie

    Finite-element modeling of liquid-crystal hydrodynamics with a variable degree of order

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    A finite-element model of liquid-crystal hydrodynamics based on the Qian and Sheng formulation has been developed. This formulation is a generalization of the Ericksen-Leslie theory to include variations in the order parameter, allowing for a proper description of disclinations. The present implementation is well suited to treat properly the various length scales necessary to model large regions yet resolve the rapid variations in the order parameter in proximity to disclinations
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