20,197 research outputs found

    Evaluation of ERBE scanner pointing accuracy based upon a coastline detection algorithm

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    Measurements from the Earth Radiation Budget Experiment (ERBE) scanning radiometers must be accurately located at the top of the Earth's atmosphere for proper interpretation of derived longwave and shortwave components of the Earth radiation field. The accuracy of the location calculations is affected by the orbit characteristics and attitude control systems of the three spacecraft, ERBS, NOAA-9, and NOAA-10. A technique was developed which makes use of the longwave scanner measurements to detect the thermal gradients at the boundaries of ocean and land masses. By analyzing many such coastline boundaries, estimates of the overall accuracy of the scanner measurement location calculations have been derived for the three satellites. The resulting measurement location errors are found to be smaller than the resolution of the radiometers, and this accuracy is well within the required location knowledge for useful science analysis of the ERBE scanner data

    A low-loss photonic silica nanofiber for higher-order modes

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    Optical nanofibers confine light to subwavelength scales, and are of interest for the design, integration, and interconnection of nanophotonic devices. Here we demonstrate high transmission (> 97%) of the first family of excited modes through a 350 nm radius fiber, by appropriate choice of the fiber and precise control of the taper geometry. We can design the nanofibers so that these modes propagate with most of their energy outside the waist region. We also present an optical setup for selectively launching these modes with less than 1% fundamental mode contamination. Our experimental results are in good agreement with simulations of the propagation. Multimode optical nanofibers expand the photonic toolbox, and may aid in the realization of a fully integrated nanoscale device for communication science, laser science or other sensing applications.Comment: 12 pages, 5 figures, movies available onlin

    The compatible conversion system

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    Compatible conversion system centralizes the solution of general problems arising from the use of direct access mass storage. It also provides a simple stable interface for the conversion of production programs to process on third generation computer system

    Application of advanced on-board processing concepts to future satellite communications systems

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    An initial definition of on-board processing requirements for an advanced satellite communications system to service domestic markets in the 1990's is presented. An exemplar system architecture with both RF on-board switching and demodulation/remodulation baseband processing was used to identify important issues related to system implementation, cost, and technology development

    Inheritance and Linkage Relationships of Morphological and Isozyme Loci in Lentil (Lens Miller)

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    Allozyme polymorphisms for 18 loci are described and their monogenic inheritance is demonstrated. We investigated linkage relationships among the 18 isozyme loci as well as four genes controlling morphological traits. Six small linkage groups were identified, containing 14 of the loci analyzed. Several of these groups appear to be conserved between Lens and Pisum, indicating that this intergeneric comparison may expedite genetic studies and breeding programs in both crop

    Scanning Tunneling Spectroscopy and Vortex Imaging in the Iron-Pnictide Superconductor BaFe1.8_{1.8}Co0.2_{0.2}As2_2

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    We present an atomic resolution scanning tunneling spectroscopy study of superconducting BaFe1.8_{1.8}Co0.2_{0.2}As2_2 single crystals in magnetic fields up to 9Tesla9 \text{Tesla}. At zero field, a single gap with coherence peaks at Δ‾=6.25meV\overline{\Delta}=6.25 \text{meV} is observed in the density of states. At 9T9 \text{T} and 6T6 \text{T}, we image a disordered vortex lattice, consistent with isotropic, single flux quantum vortices. Vortex locations are uncorrelated with strong scattering surface impurities, demonstrating bulk pinning. The vortex-induced sub-gap density of states fits an exponential decay from the vortex center, from which we extract a coherence length ξ=27.6±2.9A˚\xi=27.6\pm 2.9 \text{\AA}, corresponding to an upper critical field Hc2=43TH_{c2}=43 \text{T}.Comment: 4 pages, 4 figure

    Kepler Uniform Modeling of KOIs: MCMC Notes for Data Release 25

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    This document describes data products related to the reported planetary parameters and uncertainties for the Kepler Objects of Interest (KOIs) based on a Markov-Chain-Monte-Carlo (MCMC) analysis. Reported parameters, uncertainties and data products can be found at the NASA Exoplanet Archive . The codes used for this data analysis are available on the Github website (Rowe 2016). The relevant paper for details of the calculations is Rowe et al. (2015). The main differences between the model fits discussed here and those in the DR24 catalogue are that the DR25 light curves were used in the analysis, our processing of the MAST light curves took into account different data flags, the number of chains calculated was doubled to 200 000, and the parameters which are reported are based on a damped least-squares fit, instead of the median value from the Markov chain or the chain with the lowest 2 as reported in the past
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