25,107 research outputs found

    Planck pre-launch status: HFI beam expectations from the optical optimisation of the focal plane

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    Planck is a European Space Agency (ESA) satellite, launched in May 2009, which will map the cosmic microwave background anisotropies in intensity and polarisation with unprecedented detail and sensitivity. It will also provide full-sky maps of astrophysical foregrounds. An accurate knowledge of the telescope beam patterns is an essential element for a correct analysis of the acquired astrophysical data. We present a detailed description of the optical design of the High Frequency Instrument (HFI) together with some of the optical performances measured during the calibration campaigns. We report on the evolution of the knowledge of the pre-launch HFI beam patterns when coupled to ideal telescope elements, and on their significance for the HFI data analysis procedure

    Evolution of Prehension Ability in an Anthropomorphic Neurorobotic Arm

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    In this paper we show how a simulated anthropomorphic robotic arm controlled by an artificial neural network can develop effective reaching and grasping behaviour through a trial and error process in which the free parameters encode the control rules which regulate the fine-grained interaction between the robot and the environment and variations of the free parameters are retained or discarded on the basis of their effects at the level of the global behaviour exhibited by the robot situated in the environment. The obtained results demonstrate how the proposed methodology allows the robot to produce effective behaviours thanks to its ability to exploit the morphological properties of the robot’s body (i.e. its anthropomorphic shape, the elastic properties of its muscle-like actuators, and the compliance of its actuated joints) and the properties which arise from the physical interaction between the robot and the environment mediated by appropriate control rules

    Custom, Normative Practice, and the Law

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    Legally binding custom is conventionally analyzed in terms of two independent elements: regularities of behavior (usus) and convictions of actors engaging in the behavior that it is legally required (opinio juris). This additive conception of custom is deeply flawed. This Essay argues that we must abandon the additive conception and replace it with an account of custom that understands legally relevant customs as norms that arise from discursive normative practices embedded in rich contexts of social interaction characterized by intermeshing anticipations and interconnected conduct. The hallmark of legally binding customs, it is argued, is not the addition of belief or conviction to behavior, but rather the integration of meaningful conduct into a web of legally recognized reasons and arguments

    Custom, Normative Practice, and the Law

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    Legally binding custom is conventionally analyzed in terms of two independent elements: regularities of behavior (usus) and convictions of actors engaging in the behavior that it is legally required (opinio juris). This additive conception of custom is deeply flawed. This Essay argues that we must abandon the additive conception and replace it with an account of custom that understands legally relevant customs as norms that arise from discursive normative practices embedded in rich contexts of social interaction characterized by intermeshing anticipations and interconnected conduct. The hallmark of legally binding customs, it is argued, is not the addition of belief or conviction to behavior, but rather the integration of meaningful conduct into a web of legally recognized reasons and arguments

    Anticipatory synergy adjustments reflect individual performance of feedforward force control

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    We grasp and dexterously manipulate an object through multi-1 digit synergy. In the framework of the uncontrolled manifold (UCM) hypothesis, multi-digit synergy is defined as the coordinated control mechanism of fingers to stabilize variable important for task success, e.g., total force. Previous studies reported anticipatory synergy adjustments (ASAs) that correspond to a drop of the synergy index before a quick change of the total force. The present study compared ASA’s properties with individual performances of feedforward force control to investigate a relationship of those. Subjects performed a total finger force production task that consisted of a phase in which subjects tracked target line with visual information and a phase in which subjects produced total force pulse without visual information. We quantified their multi-digit synergy through UCM analysis and observed significant ASAs before producing total force pulse. The time of the ASA initiation and the magnitude of the drop of the synergy index were significantly correlated with the error of force pulse, but not with the tracking error. Almost all subjects showed a significant increase of the variance that affected the total force. Our study directly showed that ASA reflects the individual performance of feedforward force control independently of target-tracking performance and suggests that the multi-digit synergy was weakened to adjust the multi-digit movements based on a prediction error so as to reduce the future error

    Numerical study of asymmetric keel hydrodynamic performance through advanced CFD

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    The hydrodynamics of an asymmetric IACC yacht keel at angle of yaw are presented using simulations performed by advanced computational fluid dynamics using state-of-the-art software. The aim of the paper is to continue working on the improvement of numerical viscous flow predictions for high-performance yachts using Large Eddy Simulation and Detached Eddy Simulation on unstructured grids. Quantitative comparisons of global forces acting on the keel and wake survey are carried out. Qualitative comparisons include flow visualisation, unsteady and separated flow and other features. Star-CCM+ and the trimmed cell method give better forces and wake prediction compared to the unstructured mesh of ANSYS Fluent. Both solvers give good flow visualisation near and far field of the keel

    Development of tests for measurement of primary perceptual-motor performance

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    Tests for measuring primary perceptual-motor performance for assessing space environment effects on human performanc
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