6,380 research outputs found

    Husserlian Aspects of Wittgenstein"s Middle Period

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    It is not immediately obvious that there was anything\ud connecting Husserl or phenomenology with Wittgenstein"s\ud work, but with an examination of the evidence, this attitude\ud can be changed. I will establish the modest probability that\ud Wittgenstein had contact with the ideas of Husserl, and\ud that the ideas of Husserl were either directly or indirectly\ud influential in Wittgenstein"s work. Wittgenstein"s concern\ud with phenomenology is most explicitly expressed in his\ud Philosophical Remarks (hereafter Remarks), however\ud there is tacit concern throughout most of his writing

    Relaxing The Hamilton Jacobi Bellman Equation To Construct Inner And Outer Bounds On Reachable Sets

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    We consider the problem of overbounding and underbounding both the backward and forward reachable set for a given polynomial vector field, nonlinear in both state and input, with a given semialgebriac set of initial conditions and with inputs constrained pointwise to lie in a semialgebraic set. Specifically, we represent the forward reachable set using the value function which gives the optimal cost to go of an optimal control problems and if smooth satisfies the Hamilton-Jacobi- Bellman PDE. We then show that there exist polynomial upper and lower bounds to this value function and furthermore, these polynomial sub-value and super-value functions provide provable upper and lower bounds to the forward reachable set. Finally, by minimizing the distance between these sub-value and super-value functions in the L1-norm, we are able to construct inner and outer bounds for the reachable set and show numerically on several examples that for relatively small degree, the Hausdorff distance between these bounds is negligible

    Experiments with calibrated digital sideband separating downconversion

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    This article reports on the first step in a focused program to re-optimize radio astronomy receiver architecture to better take advantage of the latest advancements in commercial digital technology. Specifically, an L-Band sideband-separating downconverter has been built using a combination of careful (but ultimately very simple) analog design and digital signal processing to achieve wideband downconversion of an RFI-rich frequency spectrum to baseband in a single mixing step, with a fixed-frequency Local Oscillator and stable sideband isolation exceeding 50 dB over a 12 degree C temperature range.Comment: 10 pages, 12 figures, to be published in PAS