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| Публикация: №1 | А.Б. Андреев, Компютърно проектиране, Университетско издателство "Васил Априлов" - Габрово, 2009, ISBN 978-954-683-421-8. | | Издателство: | Университетско издателство "Васил Априлов" - Габрово | | Изд.год.: | 2009 | | Вид: | Учебна литература - Учебник (българско издание) | |
| Публикация: №2 | А. Андреев, Св. Рачев, М. Рачева, Числени методи в електротехниката – част I, ЕКС-ПРЕС - Габрово, 2008, ISBN 978-954-490-001-4. | | Издателство: | ЕКС-ПРЕС - Габрово | | Изд.год.: | 2008 | | Вид: | Учебна литература - Учебник (българско издание) | |
| Публикация: №3 | Andreev, A. B., Racheva, M. R.: On Some Quadratic Eigenvalue Problems. Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2024, 13952 LNCS, pp. 455–462 | | Издателство: | Springer | | Изд.год.: | 2024 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №4 | A.B. Andreev, M.R. Racheva, Two-sided Bounds of Eigenvalues Using Conforming and Nonconforming Finite Elements, International Journal of Differential Equations and Applicationsmic, Vol. 21 No 1 (2022), pp. 47-64. | | Издателство: | Academic Publications Ltd. | | Изд.год.: | 2022 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №5 | Rachev, S., M. Racheva, A. Andreev, D. Ganchev. Mathematical software tools applicable to remote learning and scientific research in case of isolation, Mathematical Modeling, year V, Issue 1/2021, pp. 8-12. ISSN 2535-0986. | | Издателство: | Mathematical Modeling | | Изд.год.: | 2021 | | Вид: | Научна публикация - Статия в бълг. списание | |
| Публикация: №6 | A.B. Andreev, M.R. Racheva, Interpolated finite element method for some fourth-order elliptic problems, Dynamic Systems and Applications, 27, No. 2 (2018), pp. 423-444. | | Издателство: | Academic Solutions Ltd. and Dynamic Publishers, Inc. | | Изд.год.: | 2018 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №7 | A.B. Andreev, M.R. Racheva, Mixed variational properties for some fourth-order beam problems, International Scientific Journal "Mathematical Modeling"– Scientific Technical Union of Mechanical Engineering, Vol. 4(2018), 122-125. ISSN 2535-0986 | | Издателство: | Scientific Technical Union of Mechanical Engineering | | Изд.год.: | 2018 | | Вид: | Научна публикация - Статия в бълг. списание | |
| Публикация: №8 | A. B. Andreev and M. R. Racheva, A Method for Linearization of a Beam Problem, Springer Leture Notes in Computer Science 10187, 180-186, 2017. ISSN: 0302-9743 | | Издателство: | Lecture Notes in Computer Science -- Springer | | Изд.год.: | 2017 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №9 | A. Andreev, H. Hristov, G. Iliev, M. Racheva - Mathematical Model for a Pneumatic Force Actuator System,Journal of the Technical University of Gabrovo, Vol. 53’2016 (46-49) | | Издателство: | Journal of the Technical University of Gabrovo, Vol. 53’2016 (46-49) | | Изд.год.: | 2016 | | Вид: | Научна публикация - Статия в бълг. списание | |
| Публикация: №10 | A.B. Andreev, M.R. Racheva, On the mathematical model of rotating shaft, International Scientific Journal “Industry 4.0” – Scientific Technical Union of Mechanical Engineering, Vol. 2(2016), 81-84. ISSN 2543-8582 | | Издателство: | International Scientific Journal “Industry 4.0” – Scientific Technical Union of Mechanical Engineering | | Изд.год.: | 2016 | | Вид: | Научна публикация - Статия в бълг. списание | |
| Публикация: №11 | A.B. Andreev, M.R. Racheva, A method for finding the eigenvalues of 3x3 real matrices. | | Издателство: | International Conference UNITECH 2016 | | Изд.год.: | 2016 | | Вид: | Научна публикация - Доклад от межд. конф. в Б-я | |
| Публикация: №12 | A. B. Andreev and M. R. Racheva, The Effect of a Postprocessing Procedure to Upper Bounds of the Eigenvalues, Springer LNCS 8962, 273-281, 2015. | | Издателство: | Springer LNCS | | Изд.год.: | 2015 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №13 | A. B. Andreev and M. R. Racheva, On a Type of Nonconforming Morley Rectangular Finite Element, Springer LNCS 8962, 282-289, 2015. | | Издателство: | Springer LNCS | | Изд.год.: | 2015 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №14 | A. Andreev and M. Racheva, Two-sided bounds of eigenvalues of second- and fourth-order elliptic operators, Appl. Math., Vol. 59, No. 4, pp. 371-390, 2014. IF 0.222 | | Издателство: | Application of Mathematics | | Изд.год.: | 2014 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №15 | A. Andreev, M. Racheva, Nonconforming rectangular Morley finite elements, Springer LNCS 8236, 158-165, 2013. | | Издателство: | Lecture NOtes in Computer Science, Springer | | Изд.год.: | 2013 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №16 | A.B. Andreev, M.R. Racheva, Lower bounds for eigenvalues and postprocessing by an integral type nonconforming FEM, Numerical Analysis and Applications, Vol. 5, Issue 3, 191-203 (2012). | | Издателство: | Numerical Analysis and Applications, Springer | | Изд.год.: | 2012 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №17 | A. Andreev, M. Racheva, Why shouldn’t some nonconforming finite elements be involved in patch-recovery technique?, International Conference UNITECH 2012, 16-17 Nov. 2012, Gabrovo, Vol. 3, 419-422. | | Издателство: | International Conference UNITECH | | Изд.год.: | 2012 | | Вид: | Научна публикация - Доклад от межд. конф. в Б-я | |
| Публикация: №18 | A. Andreev, Nonuniqueness of the mixed variational form for some fourth-order eigenvalue problems, Journal of TU-Gabrovo, Vol. 43 (2012), 3-6. | | Издателство: | Journal of TU-Gabrovo | | Изд.год.: | 2012 | | Вид: | Научна публикация - Статия в бълг. списание | |
| Публикация: №19 | A.B. Andreev, M.R. Racheva, Properties and estimates of an integral type nonconforming finite element, Lecture Notes in Comp. Sci. 7116, Springer, 523-530, 2012. | | Издателство: | Lecture Notes in Comp. Sci. 7116, Springer | | Изд.год.: | 2012 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №20 | A.B. Andreev, M.R. Racheva, Quadratic finite element approximation of a contact eigenvalue problem, Lecture Notes in Comp. Sci. 7116, Springer, 531-538, 2012. | | Издателство: | Lecture Notes in Comp. Sci. 7116, Springer | | Изд.год.: | 2012 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №21 | А.Б. Андреев, М.Р. Рачева, Нижние границы для собственных значений и постобработка неконформным методом конечных элементов (МКЭ) интегрального типа, Сибирский журнал вычислительной математики, Т. 15, No 3, с. 235-249. | | Издателство: | Сибирский журнал вычислительной математики | | Изд.год.: | 2012 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №22 | A.B. Andreev, M.R. Racheva, G.S. Tsanev, A nonconforming finite element with integral type bubble function, Proceedings of 5th Annual Meeting of the Bulgarian Section of SIAM’10, 2011, 3-6. | | Издателство: | Proceedings of 5th Annual Meeting of the Bulgarian Section of SIAM’10 | | Изд.год.: | 2011 | | Вид: | Научна публикация - Доклад от национална конф. | |
| Публикация: №23 | A.B. Andreev, M.R. Racheva, Zienkiewicz-type finite element applied to fourth-order problems, Lecture Notes in Comp. Sci. 5910, Springer, 2010, 687-694. | | Издателство: | Lecture Notes in Comp. Sci. 5910, Springer | | Изд.год.: | 2010 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №24 | A.B. Andreev, M.R. Racheva, Acceleration of convergence for eigenpairs approximated by means of non-conforming finite element methods, Lecture Notes in Comp. Sci. 5910, Springer, 2010, 695-702. | | Издателство: | Lecture Notes in Comp. Sci. 5910, Springer | | Изд.год.: | 2010 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №25 | A. Andreev and M. Racheva, On a property of the elliptic bilinear form by nonconforming finite elements, International Conference UNITECH 2010, 19-20 Nov. 2010, Gabrovo, Vol. 3, III-467-III-470. | | Издателство: | International Conference UNITECH 2010 | | Изд.год.: | 2010 | | Вид: | Научна публикация - Доклад от межд. конф. в Б-я | |
| Публикация: №26 | A.B. Andreev, M.R. Racheva, A Zienkiewicz-type finite element applied to fourth-order problems, Journal of Computational and Applied Mathematics, 235 (2010), 348-357. | | Издателство: | Journal of Computational and Applied Mathematics | | Изд.год.: | 2010 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №27 | A.B. Andreev, M.R. Racheva, Lower bounds for eigenvalues by nonconforming FEM on convex domain, AIP Conf. Proc. -- November 25, 2010 - Vol. 1301, 361-369. | | Издателство: | AIP Conf. Proc. -- November 25, 2010 | | Изд.год.: | 2010 | | Вид: | Научна публикация - Доклад от межд. конф. в Б-я | |
| Публикация: №28 | A.B. Andreev, M.R. Racheva, Acceleration of the convergence for interpolated nonconforming finite elements, Proceedings of 4th Annual Meeting of the Bulgarian Section of SIAM’09, 1-5, 2010. | | Издателство: | Proceedings of 4th Annual Meeting of the Bulgarian Section of SIAM’09 | | Изд.год.: | 2010 | | Вид: | Научна публикация - Доклад от национална конф. | |
| Публикация: №29 | A.B. Andreev, M.R. Racheva, Optimal order FEM for a coupled eigenvalue problem on 2D overlapping domains, Lecture Notes in Comp. Sci. 5434, Springer, 2009, 151-158. | | Издателство: | Lecture Notes in Comp. Sci. 5434, Springer | | Изд.год.: | 2009 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №30 | A.B. Andreev, M.R. Racheva, New approach of FEM for eigenvalue problems with non-local transition conditions, Lecture Notes in Comp. Sci. 5434, Springer, 2009, 159-167. | | Издателство: | Lecture Notes in Comp. Sci. 5434, Springer | | Изд.год.: | 2009 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №31 | A.B. Andreev, M.R. Racheva, Non-conforming Z-type FE for fourth-order problems: Estimates and application, Proceedings of 3rd Annual Meeting of the Bulgarian Section of SIAM’08, 7-10, 2009. | | Издателство: | Proceedings of 3rd Annual Meeting of the Bulgarian Section of SIAM’08 | | Изд.год.: | 2009 | | Вид: | Научна публикация - Доклад от национална конф. | |
| Публикация: №32 | A.B. Andreev, M.R. Racheva, Finite elements with integral degrees of freedom, International Conference UNITECH’09, 20-21 Nov. 2009, Gabrovo, Vol. 3, pp. ІІІ-480 - ІІІ-484. | | Издателство: | International Conference UNITECH’09 | | Изд.год.: | 2009 | | Вид: | Научна публикация - Доклад от межд. конф. в Б-я | |
| Публикация: №33 | A.B. Andreev, M.R. Racheva, Superconvergent finite element postprocessing for eigenvalue problems with nonlocal boundary conditions, Lecture Notes in Comp. Sci. 4818, Springer, 2008, 625-631. | | Издателство: | Lecture Notes in Comp. Sci. 4818, Springer | | Изд.год.: | 2008 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №34 | A.B. Andreev, M.R. Racheva, Optimal order finite element method for a coupled eigenvalue problem on overlapping domains, Lecture Notes in Comp. Sci. 4818, Springer, 2008, 637-644. | | Издателство: | Lecture Notes in Comp. Sci. 4818, Springer | | Изд.год.: | 2008 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №35 | A.B. Andreev, M.R. Racheva, Optimal order FEM for coupled eigenvalue problems on overlapping domains, Proceedings of 2nd Annual Meeting of the Bulgarian Section of SIAM’07, 2008, pp. C48-C51. | | Издателство: | Proceedings of 2nd Annual Meeting of the Bulgarian Section of SIAM’07 | | Изд.год.: | 2008 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №36 | A. Andreev, M. Racheva, Integral type finite elements and Its relation to the superconvergence technique, Proceedings of 8th International Conference "Research and Development in Mechanical Industry" RaDMI’08, Uzice, Serbia (2008), 673--679. | | Издателство: | Proceedings of 8th International Conference "Research and Development in Mechanical Industry&qu | | Изд.год.: | 2008 | | Вид: | Научна публикация - Доклад от межд.конф. в чужбина | |
| Публикация: №37 | A.B. Andreev, M.R. Racheva, On the numerical solutions of eigenvalue problems in unbounded domains, Lecture Notes in Comp. Sci. 4310, Springer-Verlag, 2007, 500-507. | | Издателство: | Lecture Notes in Computer Science, Springer | | Изд.год.: | 2007 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №38 | A.B. Andreev, R.D. Lazarov and M.R. Racheva, Postprocessing and improved accuracy of the lowest-order mixed finite element method for biharmonic eigenvalues, Lecture Notes in Comp. Sci., Springer-Verlag, 2006, Vol. 3743, 613-620. | | Издателство: | Lecture Notes in Comp. Sci., Springer-Verlag | | Изд.год.: | 2006 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №39 | A.B. Andreev, T.D. Todorov, Isoparametric finite element approximation for a boundary flux problem, International J. of Numer. Methods for Heat & Fluid Flow, Vol. 16(2), 2006. | | Издателство: | International J. of Numer. Methods for Heat & Fluid Flow | | Изд.год.: | 2006 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №40 | Andreev A. B., Maximov J. T., Racheva M.R. Finite Element Modelling for a Beam on the Winckler’s Type Base with Variable Rigidity. Siberian Journal of Numerical Mathematics (1) 2005 23-30. | | Издателство: | Russian Academy of Sciences/SPRINGER | | Изд.год.: | 2005 | | Вид: | Научна публикация - Статия в чужд. списание | | Абстракт: | We study constructing a beam on the Winckler basis that is under the influence of a cross-force. This
force rotates around the axis of the beam. The rigidity of this basis depends on the time variable. A general
mathematical model is deduced for this type of constructions. Variational formulations of the boundary value
problems in question are obtained. The finite element method is used to determine the stresses of a beam.
We discuss the corresponding eigenvalue problems in order to apply the method of normal shapes. Finally, a
numerical result with practical application is presented. | | Пълен текст: | | |
| Публикация: №41 | A. B. Andreev, M. S. Petrov and T. D. Todorov, An Optimal Order Numerical Quadrature Approximation of a Planar Isoparametric Eigenvalue Problem on Triangular Finite Element Meshes, Calcolo, vol. 42, 2, 2005, pp. 47-69. ISSN 0008-0624 Impact Factor 0.621, Quartile 2, Scopus, Publisher Springer | | Издателство: | Calcolo, Publisher Springer | | Изд.год.: | 2005 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №42 | A. B. Andreev, M. S. Petrov and T. D. Todorov, General Results for Lumped Mass Approximation of Planar Isoparametric Eigenvalue Problem on Triangular Meshes, Sib. Journal of Numerical Mathematics, 3, vol. 8, 2005, pp. 189-206. ISSN 0037-4466 | | Издателство: | ib. Journal of Numerical Mathematics | | Изд.год.: | 2005 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №43 | A. B. Andreev and T. D. Todorov, Superconvergence of the Gradient for Cubic Triangular Finite Elements, Sib. Journal of Numerical Mathematics, Vol. 8, № 2, 2005, pp. 89-100. ISSN 0037-4466, Zentralblatt | | Издателство: | Sib. Journal of Numerical Mathematics | | Изд.год.: | 2005 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №44 | A. B. Andreev and T. D. Todorov, Isoparametric Numerical Integration on Triangular Finite Element Meshes, Comptes rendus de l'Academie bulgare des Sciences, №7, vol. 57, 2004, pp. 37-44. ISSN 1310-1331, Zentralblatt | | Издателство: | Bulgarian Academy of Sciences | | Изд.год.: | 2004 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №45 | A. B. Andreev and T. D. Todorov, Isoparametric Finite-Element Approximation of а Steklov Eigenvalue Problem, IMA Journal of Numerical Analysis, v. 24, № 2, 2004, pp. 309-322. ISSN 0272-4979 Impact Factor 0.883 Quartile 2, Scopus, Publisher Oxford University Press | | Издателство: | Oxford University Press | | Изд.год.: | 2004 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №46 | Andreev A. B., Maximov J. T., Racheva M.R. Modelling of the elastic line for twist drill with straight shank fixed in three-jaw chuck. Lecture Notes in Computer Science 3401 (2004) 116-124. | | Издателство: | SPRINGER | | Изд.год.: | 2004 | | Вид: | Научна публикация - Статия в чужд. списание | | Абстракт: | The aim of this study is to present a new approach for investigation of an important problem of mechanical engineering. Namely, the model of twist drill embeded in three-jaw chuck is discussed. This problem could be considered as a variant of a beam on the Winckler’s base which is under the influence of a cross-force.
Our principal aim is to deduce the general mathematical model for this type of constructions. In order to determine the dynamic stresses of the drill using any variational numerical methods we present the corresponding variational formulations. These presentations are characterized by mixed formulation. So, the mixed finite element method is convenient for this kind of problems. The possibility for symmetrization of the weak formulation of the model problem is also discussed. | |
| Публикация: №47 | Andreev A. B., Maximov J. T., Racheva M.R. Two Approaches to the Finite Element Analysis of the Stiffened Plates. Lecture Notes in Computer Science. 2542 (2003) 353-362 | | Издателство: | SPRINGER | | Изд.год.: | 2003 | | Вид: | Научна публикация - Статия в чужд. списание | |
| Публикация: №48 | Andreev A. B., Maximov J. T., Racheva M. R. Finite element method for calculation of dynamic stresses in the continuous beam on elastic support. Siberian Journal of Numerical Mathematics 2 (6) (2003) 113-124 | | Издателство: | Russian Academy of Sciences/SPRINGER | | Изд.год.: | 2003 | | Вид: | Научна публикация - Статия в чужд. списание | | Абстракт: | We study a damping beam construction on elastic supports. For this kind of a construction a general
mathematical model is deduced. The external load is a time-depending harmonic function. The corresponding
spectral problem contains the eigenvalue parameter in the boundary conditions. The variational formulations
of the considered boundary value problems are obtained. The dynamic stresses of the constructions are
determined using the finite element method and the method of normal shapes. Finally, the numerical results
related to the problem with practical applications are presented. | |
| Публикация: №49 | Andreev A. B., Maximov J. T., Racheva M.R. Finite Element Method for Plates with Dynamic Loads. Lecture Notes in Computer Science 2179 (2001) 445-453 | | Издателство: | SPRINGER | | Изд.год.: | 2001 | | Вид: | Научна публикация - Статия в чужд. списание | |
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