599 research outputs found

    Bistability conditions between lasing and non-lasing states for vertical-cavity surface-emitting lasers with frequency-selective optical feedback

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    This paper gives analytical treatment and experimental details on on/off-bistability in vertical-cavity surface-emitting lasers with frequency-selective feedback by a grating. In particular, the conditions for the coexistence of lasing and nonlasing states and an abrupt turn-on behaviour at threshold are derived using an envelope approximation. The theoretical and experimental results are in satisfactory agreement

    ExoMol molecular line lists - XVI: The rotation-vibration spectrum of hot H2_2S

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    This work presents the AYT2 line list: a comprehensive list of 114 million 1^{1}H2_232^{32}S vibration-rotation transitions computed using an empirically-adjusted potential energy surface and an {\it ab initio} dipole moment surface. The line list gives complete coverage up to 11000 \cm\ (wavelengths longer than 0.91 μ\mum) for temperatures up to 2000 K. Room temperature spectra can be simulated up to 20000 \cm\ (0.5 μ\mum) but the predictions at visible wavelengths are less reliable. AYT2 is made available in electronic form as supplementary data to this article and at \url{www.exomol.com}.Comment: 12 pages, 10 figures, 10 table

    Experimental Research of the Diffraction and Vavilov-Cherenkov Radiation Generation in a Teflon Target

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    Geometry of Vavilov-Cherekov (VChR) radiation when an electron moves close to a dielectric target is in analogy to diffraction radiation (DR) geometry. In this case we may expect DR generation from the upstream face of the target besides that VChR. The joint observation of these booth types of radiation is very interesting from the pseudo-photon viewpoint, which is applicable for relativistic electrons. Unexpected results obtained in our experiment insist on reflection about nature both DR and VChR. The experiment was performed on the relativistic electron beam of the microtron of Tomsk Polytechnic University.Comment: This article will be published in Journal of Physic

    ПЛАНИРОВАНИЕ ЗНАНИЕВОГО КОНТЕНТА ОБРАЗОВАТЕЛЬНОЙ ПРОГРАММЫ С ИСПОЛЬЗОВАНИЕМ ОНТОЛОГИЧЕСКОГО ИНЖИНИРИНГА И ПРОЕКТНО-КОМПЕТЕНТНОСТНОГО ПОДХОДА

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    В статье рассматривается инновационная методика формирования знаниевых компонентов планируемого обучения, основанная на концепциях и механизмах онтологического инжиниринга, проектно-ориентированной технологии обучения и компетентностной модели выпускника. Показаны возможности образовательной среды, связанные, во-первых, с традиционным формирование знаниевого контента дисциплин учебного плана; во-вторых, в случае использования проектно-ориентированной технологии обучения, планировать знаниевый тренд и формировать знаниевый контент профилирующих и базовых дисциплин учебного плана специальности в соответствии с компетенциями компетентностных моделей этапов CDIO и, в-третьих, используя проектно-ориентированную технологию обучения и компетентностный подход, планировать знаниевый тренд и формировать знаниевый контент сценария индивидуальной траектории обучения. В этом случае, для конфигурирования сценария обучения используются знаниевые компоненты и параметры smart-контракта. На примере дисциплины «Технологии разработки распределенных приложений» и проекта «Банковская система типа клиент-сервер» приведены формализмы и концепции образовательной среды, связанные с формированием знаниевого контента данной дисциплины, в соответствии с компетентностными моделями этапов CDIO. Данная методика нашла свое отражение в образовательной среде, выполненной в виде web-приложения, и апробацию в учебном процессе на кафедре «Компьютерная и программная инженерия» университета «Туран»

    A generalized framework towards structural mechanics of three-layered composite structures

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    Three-layered composite structures find a broad application. Increasingly, composites are being used whose layer thicknesses and material properties diverge strongly. In the perspective of structural mechanics, classical approaches to analysis fail at such extraordinary composites. Therefore, emphasis of the present approach is on arbitrary transverse shear rigidities and structural thicknesses of the individual layers. Therewith we employ a layer-wise approach for multiple (quasi-) homogeneous layers. Every layer is considered separately whereby this disquisition is based on the direct approach for deformable directed surfaces. We limit our considerations to geometrical and physical linearity. In this simple and familiar setting we furnish a layer-wise theory by introducing constraints at interfaces to couple the layers. Hereby we restrict our concern to surfaces where all material points per surface are coplanar and all surfaces are plane parallel. Closed-form solutions of the governing equations enforce a narrow frame since they are strongly restrictive in the context of available boundary conditions. Thus a computational solution approach is introduced using the finite element method. In order to determine the required spatially approximated equation of motion, the principle of virtual work is exploited. The discretization is realized via quadrilateral elements with quadratic shape functions. Hereby we introduce an approach where nine degrees of freedom per node are used. In combination with the numerical solution approach, this layer-wise theory has emerged as a powerful tool to analyze composite structures. In present treatise, we would like to clarify the broad scope of this approach

    Study of few-body nuclei by Feynman’s continual integrals and hyperspherical functions

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    Feynman’s continual integrals method for solving N-body ground state problem was implemented using parallel computing. The correctness of calculations for 3-body systems 6Li, 12C was checked by comparison with the results of the expansion into hyperspherical functions. New effective method for the solution of the system of hyperradial equations with cubic splines approximation is used. Feynman’s continual integrals method was also used to study the 7Li nucleus as a 4-body system
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