1,861 research outputs found

    Resurrection purpose

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    Humanly speaking, besides a few of the disciples, Jesus\u27s closest friends were undoubtedly Mary, Martha and Lazarus. They were like family, and their house in Bethany was a place of safety and refuge. One day the sisters sent word to Jesus that Lazarus was extremely sick and about to die. After a two-day delay Jesus began his four-day journey to Bethany. I don\u27t always know what to make of God\u27s delays, but I\u27m convinced they don\u27t mean he doesn\u27t love us. We hope for a greater purpose. The worst happens, Lazarus dies

    A Walsh-Domain Adaptive Filter

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    Two Walsh-domain dyadic convolution adaptive filters are developed using a circular convolution frequency-domain filter (FDF1) and the Fast LMS adaptive filter (FDF2): WDF1 and WDF2 respectively. General theory of time- domain adaptive filters and a theoretical analysis of the FDF1, FDF2, WDF1, and WDF2 filters are presented. WDF1 and WDF2 software implementation are shown to be error free. A time-domain filter (TDF) and a FDF2 frequency-domain filter (FDF) are implemented for comparison testing. The WDF1, WDF2, TDF, and FDF filters are tested using time-shifted sinusoidal and rectangular noisy and noiseless signals. WDF1 and WDF2 are shown to converge faster and produce less error filtering discontinuous signals, relative to the TDF and FDF performance. WDF1 and WDF2 are shown to converge slower and produce more error filtering continuous signals, relative to TDF and FDF performance. WDF1 is shown to perform better for noiseless signals, relative to WDF2 performance. WDF2 is shown to perform better for noise signals, relative to WDF1 performance. WDF1 and WDF2 filtering performance was shown to degrade with increasing time shift. A processing speed comparison showed WDF1 to be faster than the TDF, FDF, and WDF2 filters

    Memorandum to All Banders, August 1963

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    Subject: Bird Banding Report

    Memorandum to All Banders, December 1954

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    Regarding changes in operations for processing banding dat

    Time-distance helioseismology: Sensitivity of f-mode travel times to flows

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    Time-distance helioseismology has shown that f-mode travel times contain information about horizontal flows in the Sun. The purpose of this study is to provide a simple interpretation of these travel times. We study the interaction of surface-gravity waves with horizontal flows in an incompressible, plane-parallel solar atmosphere. We show that for uniform flows less than roughly 250 m s−1^{-1}, the travel-time shifts are linear in the flow amplitude. For stronger flows, perturbation theory up to third order is needed to model waveforms. The case of small-amplitude spatially-varying flows is treated using the first-order Born approximation. We derive two-dimensional Fr\'{e}chet kernels that give the sensitivity of travel-time shifts to local flows. We show that the effect of flows on travel times depends on wave damping and on the direction from which the observations are made. The main physical effect is the advection of the waves by the flow rather than the advection of wave sources or the effect of flows on wave damping. We compare the two-dimensional sensitivity kernels with simplified three-dimensional kernels that only account for wave advection and assume a vertical line of sight. We find that the three-dimensional f-mode kernels approximately separate in the horizontal and vertical coordinates, with the horizontal variations given by the simplified two-dimensional kernels. This consistency between quite different models gives us confidence in the usefulness of these kernels for interpreting quiet-Sun observations.Comment: 34 pages, accepted to Astrophysical Journa
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