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  • Informational database model for accounting of the teachers workload of an educational organization

    This paper presents an information model of a relational database developed by the authors, designed to take into account the teachers workload of an educational organization. The identification of the subject area entities, their decomposition and the relationships identification between them are carried out. The constructed database model was brought to the Boyes - Codd normal form. Based on the designed database schema, its physical implementation and filling with test data was carried out. The results of test queries showed the developed model adequacy and the its practical applicationp ossibility. It is currently in trial operation at the Department of Information Systems and Computer Modeling, Volgograd State University. With minimal changes, the developed database schema can be applied to account for the teachers workload in various educational organizations.

    Keywords: database, information modeling, "entity-relationship" diagram, decomposition, information system, educational organization

  • Phonon properties of hydrogenated carbon nanofilms

    In this work, the phonon format of graphane nanoribbons is calculated in the Hamiltonian formulaism. The geometric model is presented in the form of a graphene plane with hydrogen atoms attached to it. The unit cell of graphane contains two carbon atoms from solid graphene and two carbon atoms. The curvature of the graphene plane as a result of attachment to hydrogen atoms and hybridization of the outer electron orbitals of carbon atoms from sp2 to sp3, as well as the interaction between hydrogen atoms, are not taken into account. Analysis of the obtained phonon spectra shows that, for any type and width of graphane nanoribbons, there is a gap between acoustic and optical vibrational modes, in contrast to graphene, which can serve as an indicator for a given structure. Also, for the material under study, the values ​​of the speed of sound and the Debye temperature were calculated.

    Keywords: graphene, graphane, nanoribbon, unit cell, vibrational spectrum, dispersion equation