919 research outputs found

    Настройка моделей при создании систем поддержки принятия стратегических решений

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    Показана актуальность разработки платформы (программной среды), позволяющей на её основе создавать системы стратегического управления организациями, используя сквозные технологии поддержки принятия решений и универсальные инструментальные средства. Статья посвящена решению одной из задач, возникающей при разработке такой платформы - настройке универсальных моделей поддержки принятия решений под условия принятия решений и особенности предметной области стратегического управления. Разработан механизм настройки моделей, выявлены и представлены параметры настройки

    Introduction to the papers of TWG16: Learning Mathematics with Technology and Other Resources

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    The use of technology and other resources for mathematical learning is a current issue in the field of mathematics education and lags behind the rapid advances in Information and Communication Technology. Technological developments offer opportunities, which are not straightforward to exploit in regular teaching. In CERME10 TWG16, the recent research findings, issues and future questions have been explored and discussed in detail. In this introductory chapter, we will outline the scope and focus of the work, describe the results with respect to existing questions, and identify upcoming topics as well as missing topics that might set the agenda for future work in this domain

    Individual grain boundary properties and overall performance of metal-organic deposition coated conductors

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    have investigated single grain boundaries (GBs) isolated in coated conductors produced by metal-organic deposition. When a magnetic field is swept in the film plane, an angle-dependent crossover from boundary to grain limited critical current density J(c) is found. In the force-free orientation, even at fields as high as 8 T, the GBs still limit Jc. We deduce that this effect is a direct consequence of GB meandering. We have employed these single GB results to explain the dependence of Jc of polycrystalline tracks on their width: in-plane measurements become flatter as the tracks are narrowed down. This result is consistent with the stronger GB limitation at field configurations close to force-free found from the isolated boundaries. Our study shows that for certain geometries even at high fields the effect of GBs cannot be neglected.This work was supported by the Engineering and Physical Sciences Research Council [grant numbers EP/C011546/1 and EP/C011554/1

    Unification, KK-thresholds and the top Yukawa coupling in F-theory GUTs

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    In a class of F-theory SU(5) GUTs the low energy chiral mass spectrum is obtained from rank one fermion mass textures with a hierarchical structure organised by U(1) symmetries embedded in the exceptional E_8 group. In these theories chiral fields reside on matter `curves' and the tree level masses are computed from integrals of overlapping wavefuctions of the particles at the triple intersection points. This calculation requires knowledge of the exact form of the wavefuctions. In this work we propose a way to obtain a reliable estimate of the various quantities which determine the strength of the Yukawa couplings. We use previous analysis of KK threshold effects to determine the (ratios of) heavy mass scales of the theory which are involved in the normalization of the wave functions. We consider similar effects from the chiral spectrum of these models and discuss possible constraints on the emerging matter content. In this approach, we find that the Yukawa couplings can be determined solely from the U(1) charges of the states in the `intersection' and the torsion which is a topological invariant quantity. We apply the results to a viable SU(5) model with minimal spectrum which satisfies all the constraints imposed by our analysis. We use renormalization group analysis to estimate the top and bottom masses and find that they are in agreement with the experimental values.Comment: 28 pages, 2 figure

    Chiral symmetry breaking of magnetic vortices by sample roughness

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    Finite-element micromagnetic simulations are employed to study the chiral symmetry breaking of magnetic vortices, caused by the surface roughness of thin-film magnetic structures. An asymmetry between vortices with different core polarizations has been experimentally observed for square-shaped platelets. E.g., the threshold fields for vortex core switching were found to differ for core up and down. This asymmetry was however not expected for these symmetrically-shaped structures, where both core polarizations should behave symmetrically. Three-dimensional finite element simulations are employed to show that a small surface roughness can break the symmetry between vortex cores pointing up and down. A relatively small sample roughness is found sufficient to reproduce the experimentally observed asymmetries. It arises from the lack of mirror-symmetry of the rough thin-film structures, which causes vortices with different handedness to exhibit asymmetric dynamics

    TimeMaxyne A shot noise limited, time resolved pump and probe acquisition system capable of 50 GHz frequencies for synchrotron based X ray microscopy

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    With the advent of modern synchrotron sources, X ray microscopy was developed as a vigorous tool for imaging material structures with element specific, structural, chemical and magnetic sensitivity at resolutions down to 25 nm and below. Moreover, the X ray time structure emitted from the synchrotron source short bunches of less than 100 ps width provides a unique possibility to combine high spatial resolution with high temporal resolution for periodic processes by means of pump and probe measurements. To that end, TimeMaxyne was developed as a time resolved acquisition setup for the scanning X ray microscope MAXYMUS at the BESSY II synchrotron in order to perform high precision, high throughput pump and probe imaging. The setup combines a highly sensitive single photon detector, a real time photon sorting system and a dedicated synchronization scheme for aligning various types of sample excitations of up to 50 GHz bandwidth to the photon probe. Hence, TimeMaxyne has been demonstrated to be capable of shot noise limited, time resolved imaging, at time resolutions of 50 ps and below, only limited by the X ray pulse widths of the synchrotro
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