Browsing by Author "Vulpe, Nicolae"

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    The Family of Quadratic Systems with Two Invariant Conics: Parabola and Hyperbola [Articol]
    (2024) Vulpe, Nicolae
    We consider the family of quadratic systems QSPHη>0 having three real distinct infinite singularities and possessing at least two invariant conics: a parabola and a hyperbola. All the possible configurations of these invariant conics including invariant lines (when they exist) are determined. We describe completely the set of such systems and we prove the existence of exactly 38 distinct configurations which could possess a system in this family.
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    MODELE MATEMATICE DE EXPERTIZĂ ÎN DOMENII ŞTIINŢIFICE
    (Academia de Ştiinţe a Moldovei, 2013) Arnaut, Vsevolod; Gaindric, Constantin; Damian, Florin; Magariu, Galina; Rogojin, Iurie; Secrieru, Iulian; Verlan, Tatiana; Vulpe, Nicolae
    For the purpose of forming a team of scientific experts to evaluate each project submitted to the announced competitions, the authors propose an approach such that team members to be the most advisable to properly estimate the project amenable to evaluation. An algorithm that consists of assigning a numerical value to each expert which will express the expert’s potential (rating) is proposed. It takes into account importance of scientifi c projects in which the expert had participated, journals where he had published his results and scientifi c forums where he had participated with reports. Also, there is proposed an approach to the modes of hierarchization of journals, conferences and grants in accordance with scientific domain. Domains Mathematics and Computer Science are presented as the example.
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    Polynomial Differential Cubic Systems with Invariant Straight Lines of Total Multiplicity Seven and Four Distinct Infinite Singularities [Articol]
    (2024) Bujac, Cristina; Vulpe, Nicolae
    The family of cubic differential systems possessing invariant straight lines was considered by many authors. But a strong classification of this family according to the configurations of invariant lines began in 2006 [11], where the existence of the maximum number of invariant lines (nine) is required. Here we continue the investigation of the subfamily of cubic systems possessing invariant lines of total multiplicity seven and four distinct infinite singularities. We prove that this subfamily could have a total of 166 distinct configurations of invariant straight lines.