566 research outputs found

    The Materials Project – A Public Materials Design Platform

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    Retrieval of equivalent currents by the use of an integral representation and the extinction theorem --- radome applications

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    The aim of this thesis is to solve an inverse source problem. The approach is based on an integral representation together with the extinction theorem. Both a scalar and a full-wave integral representation are implemented and solved by a Method of Moment procedure. The body of revolution enables usage of a Fourier transform to reduce the dimensions of the problem. A singular value decomposition is utilized to suppress singular values in the inversion process. A nose-cone radome is diagnosed by recreating the equivalent surface currents on its surface from measured near fields. It is shown how the radome interacts with the field, creating beam deflection, pattern distortion, etc. The phase shift of the field due to the transmission through the radome, i.e., the insertion phase delay, is visualized. Disturbances due to defects, not detectable in the measured near field, are correctly localized by the equivalent surface currents. The alteration of side and flash lobes, together with the introduction of scattering due to the defects, are also visualized. Verification is made by comparison between the calculated and measured far field

    Reconstruction of Equivalent currents Using the Scalar Surface Integral Representation

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    Knowledge of the current distribution on a radome can be used to improve radome design, detect manufacturing errors, and to verify numerical simulations. In this paper, the transformation from near-field data to its equivalent current distribution on a surface of arbitrary material, i.e., the radome, is analyzed. The transformation is based on the scalar surface integral representation that relates the equivalent currents to the near-field data. The presence of axial symmetry enables usage of the fast Fourier transform (FFT) to reduce the computational complexity. Furthermore, the problem is regularized using the singular value decomposition (SVD). Both synthetic and measured data are used to verify the method. The quantity of data is large since the height of the radome corresponds to 29 − 43wavelengths in the frequency interval 8.0 − 12.0GHz. It is shown that the method gives an accurate description of the field radiated from an antenna, on a surface enclosing it. Moreover, disturbances introduced by copper plates attached to the radome surface, not localized in the measured near field, are focused and detectable in the equivalent currents. The method also enables us to determine the phase shift of the field due to the passage of the radome, cf. the insertion phase delay

    User Applications Driven by the Community Contribution Framework MPContribs in the Materials Project

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    This work discusses how the MPContribs framework in the Materials Project (MP) allows user-contributed data to be shown and analyzed alongside the core MP database. The Materials Project is a searchable database of electronic structure properties of over 65,000 bulk solid materials that is accessible through a web-based science-gateway. We describe the motivation for enabling user contributions to the materials data and present the framework's features and challenges in the context of two real applications. These use-cases illustrate how scientific collaborations can build applications with their own "user-contributed" data using MPContribs. The Nanoporous Materials Explorer application provides a unique search interface to a novel dataset of hundreds of thousands of materials, each with tables of user-contributed values related to material adsorption and density at varying temperature and pressure. The Unified Theoretical and Experimental x-ray Spectroscopy application discusses a full workflow for the association, dissemination and combined analyses of experimental data from the Advanced Light Source with MP's theoretical core data, using MPContribs tools for data formatting, management and exploration. The capabilities being developed for these collaborations are serving as the model for how new materials data can be incorporated into the Materials Project website with minimal staff overhead while giving powerful tools for data search and display to the user community.Comment: 12 pages, 5 figures, Proceedings of 10th Gateway Computing Environments Workshop (2015), to be published in "Concurrency in Computation: Practice and Experience

    Sensitivity Analysis for Antenna Near-Field Imaging

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    Sensitivity Analysis for Antenna Near-Field Imaging

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