5,732 research outputs found
Investigating the micromechanics of polycrystalline materials using high-energy X-ray diffraction
Quantifying the state of materials and understanding their micromechanical behavior are ever more important for designing and building efficient, high-performance machines. High-energy synchrotron radiation is an attractive nondestructive tool for investigating the state and the micromechanical behavior of polycrystalline structural alloys. In this discussion, two high energy X-ray experimental techniques that are available at Sector 1 of the Advanced Photon Source will be presented. Wide angle X-ray scattering (WAXS) technique is used to measure orientation dependent quantities such as crystallographic texture or stress orientation distribution function. High-energy diffraction microscopy (HEDM) technique is a suite of experiments where orientation, strain, and position of individual grains in a polycrystalline sample can be measured
-positivity and Schmidt number under orthogonal group symmetries
In this paper, we study -positivity and Schmidt number under standard
orthogonal group symmetries. The Schmidt number is a widely used measure of
quantum entanglement in quantum information theory. First of all, we exhibit a
complete characterization of all -positive orthogonally covariant maps. This
generalizes the earlier results in [Tom85]. Then, we optimize some averaging
techniques to establish duality relations between orthogonally covariant maps
and orthogonally invariant operators. This new framework enables us to
effectively compute the Schmidt numbers of all orthogonally invariant quantum
states
Generalized gravity model for human migration
The gravity model (GM) analogous to Newton's law of universal gravitation has
successfully described the flow between different spatial regions, such as
human migration, traffic flows, international economic trades, etc. This simple
but powerful approach relies only on the 'mass' factor represented by the scale
of the regions and the 'geometrical' factor represented by the geographical
distance. However, when the population has a subpopulation structure
distinguished by different attributes, the estimation of the flow solely from
the coarse-grained geographical factors in the GM causes the loss of
differential geographical information for each attribute. To exploit the full
information contained in the geographical information of subpopulation
structure, we generalize the GM for population flow by explicitly harnessing
the subpopulation properties characterized by both attributes and geography. As
a concrete example, we examine the marriage patterns between the bride and the
groom clans of Korea in the past. By exploiting more refined geographical and
clan information, our generalized GM properly describes the real data, a part
of which could not be explained by the conventional GM. Therefore, we would
like to emphasize the necessity of using our generalized version of the GM,
when the information on such nongeographical subpopulation structures is
available.Comment: 14 pages, 6 figures, 2 table
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