Felix Sadyrbaev  

 

 

 

Leading researcher, professor, Dr.habil.math. Leading researcher, Dr.habil.math.
Mathematical Research Center, Department of Technology Laboratory of Ordinary Differential Equations
Institute of Life Sciences and Technology Institute of Mathematics and Computer Science
Daugavpils University University of Latvia
Parades street 1 Raina bulvaris 29
LV-5400, Daugavpils, Latvia LV-1459, Riga, Latvia
felix@latnet.lv felix@latnet.lv

Scopus

https://orcid.org/0000-0001-5074-804X
Research interests  

 

Research in the theory of nonlinear boundary problems for ordinary differential equations, theory of oscillations, asymmetric problems, qualitative behavior of solutions of nonlinear differential equations, approximation of solutions, calculus of variations, problems from applications, spectral problems, analysis of three dimensional systems

Education  
 
  • Dr.habil.math., University of Latvia, Riga, Latvia
    Dissertation: Estimations of the number of solutions of nonlinear  boundary value problems.

 
  • Ph.D. (Candidate of Science), Differential Equations, Belourussian State University, Minsk
    Dissertation: On some class of boundary value problems for a system of the first order ordinary differential equations.
    Advisor: Prof. Yurii Klokov

 
  • Graduated from Latvian State University, Faculty of Physics and Mathematics, Riga, Latvia
    Thesis: Properties of Operators in Hilbert Spaces.
    Advised by Gennadiy Laptev

Teaching  
 
  • Professor at the Daugavpils University from 1999.
 
  • Courses taught: Basics of Optimization, Mathematical Modelling and Differential Equations
 
  • Coordinator of Doctoral studies in Mathematics (Daugavpils University) from 2002
Research projects  
  • Latvian Council of Science,  Project Nr. 09.1220 Contemporary Methods of Analyzing Dynamical Systems,  Head of the project, 2009-

 
  • Latvian Council of Science,  Project Nr. 05.1531 Nonlinear Boundary Value Problems for Ordinary Differential Equations, Head of the project, 2005-2008.

 
  • Latvian Council of Science,  Project  Nr. 01.0356  Nonlinear Boundary Value Problems for Ordinary Differential Equations, Head of the project, 2001-2004.

Selected publications  
  • A. Kirichuka and F. Sadyrbaev. On boundary value problem for equations with cubic nonlinearity and step-wise coefficient, Differential Equations & Applications, V. 10, N. 4, 2018, pp. 433-447.
  • N. Sveikate and F. Sadyrbaev. On conversion of resonant problem to non-resonant one, Miskolc Mathematical Notes, V. 18, N. 2, 2017, 1059-1071. Miskolc Mathematical Notes
  • E. Brokan and F. Sadyrbaev. Attraction in network describing systems, Proceedings of the 17th International Conference on Computational and Mathematical Methods in Science and Engineering (Costa Ballena, Rota, Cadiz, Spain, 4-8 July, 2017), 2017, 415-418. CMMSE 2017
  • F. Sadyrbaev. Note on resonant problems, Proceedings of the 17th International Conference on Computational and Mathematical Methods in Science and Engineering (Costa Ballena, Rota, Cadiz, Spain, 4-8 July, 2017), 2017, 1862-1864. CMMSE 2017
  • E. Brokan and F. Sadyrbaev. On attractors in gene regulatory systemsAmerican Institute of Physics Conference Proceedings, 2017, V. 1809, 020010. American Institute of Physics
  • A. Gritsans, F. Sadyrbaev and I. Yermachenko. Dirichlet boundary value problem for the second order asymptotically linear systemInternational Journal of Differential Equations, V. 2016 (2016), Article ID 5676217, 12 pages http://dx.doi.org/10.1155/2016/5676217. Hindawi
  • D. Finaskins, E. Brokan and F. Sadyrbaev. Attracting sets in network regulatory theory. 2016 Advances in Wireless and Optical Communications (RTUWO), 2016, 211 - 215. IEEE Xplore
  • E. Brokan and F. Sadyrbaev. On a differential system arising in the network control theory. Nonlinear Analysis: Modelling and Control, V. 21, N. 5, 2016, 687–701. LANA
  • M. Dobkevich and F. Sadyrbaev. On different type solutions of boundary value problems. Math. Modelling and Analysis, V. 21, N. 5,  2016, 659-667. Taylor & Francis
  • S. Atslega, D. Finaskins and F. Sadyrbaev. On a planar dynamical system arising in the network control theory. Math. Modelling and Analysis, V. 21, N. 3,  2016, 385-398. Taylor & Francis
  • S. Atslega and F. Sadyrbaev. Solutions of two-point boundary value problems via phase-plane analysis. E. J. Qualitative Theory of Diff. Equ., Proc. 10'th Coll. Qualitative Theory of Diff. Equ., N. 4, 2016, 1-10. EJQTDE
  • F. Sadyrbaev. Oscillatory solutions of boundary value problems. In: Springer Proceedings in Mathematics & Statistics, V. 164, S. Pinelas, Z. Dosla, O. Dosly, P.E. Kloeden (Eds.), Differential & Difference Equations and Applications 2016, 109-117. Springer
  • A. Gritsans and F. Sadyrbaev. The Nehari solutions and asymmetric minimizers, Proceedings of the 10th AIMS Conference on Dynamical Systems, Differential Equations and Applications (Madrid, Spain, July 7-11, 2014),  2015, 562-568. American Institute of Mathematical Sciences.
  • M. Dobkevich and F. Sadyrbaev. Types and multiplicity of solutions to Sturm–Liouville boundary value problem. Math. Modelling and Analysis, V. 20, N. 1,  2015, 1-8. Taylor & Francis
  • A. Kirichuka and F. Sadyrbaev. Multiple positive solutions for the Dirichlet boundary value problems by phase plane analysisAbstract and Applied Analysis, V. 2015 (2015), Article ID 302185, 6 pages doi:10.1155/2015/302185. Hindawi
  • E. Brokan and F. Sadyrbaev. Attracting Sets in Gene Regulatory Systems. In Proceedings of International Conference on Simulation, Modelling and Mathematical Statistics (SMMS 2015), 2015, 135-138. Link
  • I. Yermachenko and F. Sadyrbaev. On a problem for a system of two the second order differential equations via the theory of vector fields. Nonlinear Analysis. Modelling and Control, V. 20, N. 2, 2015, 175-189. LANA
  • M. Dobkevich, F. Sadyrbaev, N. Sveikate and I. Yermachenko. On types of solutions of the second order nonlinear boundary value problems. Abstract and Applied Analysis, V. 2014 (2014), Article ID 594931, 9 pages, http://dx.doi.org/10.1155/2014/594931. Hindawi
  • A. Gritsans and F. Sadyrbaev. Unexpected solutions of the Nehari problemInternational Journal of Analysis, V. 2014 (2014), Article ID 467831, 5 pages doi:10.1155/2014/467831. Hindawi pdf
  • N. Sveikate and F. Sadyrbaev. Quasilinearization for resonant boundary-value problems with mixed boundary conditions, Nonlinear Oscillations, Vol. 17, N. 1, 2014, 112-126. Nonlinear Oscillations

    N. Sveikate and F. Sadyrbaev. Quasilinearization for resonant boundary-value problems with mixed boundary conditions, Journal of Mathematical Sciences, V. 205, N. 6, 2015, 832-847. Springer
  • I. Yermachenko and F. Sadyrbaev. Quasilinearization and multiple solutions of the second order nonlinear boundary value problem, Journal of Control Engineering and Technology, Vol. 4, N. 1, 2014, 1-8. EBSCO pdf
  • S. Atslega and F. Sadyrbaev. On periodic solutions of Liénard type equations. Math. Modelling and Analysis, V. 18, N. 5,  2013, 708-716. Taylor & Francis
  • F. Sadyrbaev. Two-dimensional systems with asymmetric principal partIn: Springer Proceedings in Mathematics & Statistics, V. 47, S. Pinelas, M. Chipot, Z. Dosla (Eds.), Contributions from the International Conference on Differential & Difference Equations and Applications 2013, 99-111. Springer
  • A. Gritsans and F. Sadyrbaev. On solvability of boundary value problem for asymmetric differential equation depending on x'Math. Modelling and Analysis, V. 18, N. 2,  2013, 176-190. Taylor & Francis
  • A. Gritsans and F. Sadyrbaev. Boundary value problems for a super-sublinear asymmetric oscillator: exact number of solutions. International Journal of Mathematics and Mathematical Sciences, V. 2013 (2013), Article ID 705984, 9 pages doi:10.1155/2013/705984. Hindawi pdf
  • I. Yermachenko and F. Sadyrbaev. Quasilinearization technique for Φ-Laplacian type equations. International Journal of Mathematics and Mathematical Sciences, V. 2012 (2012), Article ID 975760, 11 pages doi:10.1155/2012/975760. Hindawi
  • A. Gritsans and F. Sadyrbaev. Nonlinear problems with asymmetric principal part. Math. Modelling and Analysis, V. 17, N. 2,  2012, 217-226. Taylor & Francis
  • Y. Kozmina and  F. Sadyrbaev. On a maximal number of period annuli, Abstract and Applied Analysis, V. 2011 (2011), Article ID 393875, 8 pages, doi:10.1155/2011/393875. Hindawi
  • A. Gritsans and F. Sadyrbaev. Two-parameter nonlinear oscillations: the Neumann problem. Math. Modelling and Analysis, V. 16, N. 1,  2011, 23-38. Taylor & Francis
  • F. Sadyrbaev and N. Sergejeva. On a Fučik type spectral problem for the second order nonlinear differential equation with the integral boundary condition. Communications in Applied Analysis, V. 15, N. 2-42011, 557-567. Dynamic Publishers pdf
  • S. Atslega, F. Sadyrbaev.  Multiple period annuli in Lienard type equations. Applied Mathematics Letters, V. 23, N. 2, 2010, 165–169. Elsevier

  • F. Sadyrbaev. Multiplicity in parameter-dependent problems for ordinary differential equations. Mathematical Modelling and Analysis, V. 14, N. 4, 2009, 503-514. Taylor & Francis
  • M. Dobkevich and F. Sadyrbaev. Types of solutions and approximation of solutions of second order nonlinear boundary value problems.  In: Amer. Inst. Phys. Conference Proceedings Volume 1168, 260 – 263. Numerical Analysis and applied mathematics: International Conference on Numerical Analysis and Applied Mathematics 2009: Part 2, Rethymno, Crete (Greece), 18 – 22 September 2009. American Institute of Physics
  • S. Atslega and F. Sadyrbaev. Multiple positive solutions in the second order autonomous nonlinear boundary value problems. In: American Institute of Physics Conference Proceedings Vol. 1168, 873-876. Numerical Analysis and Applied Mathematics: International Conference on Numerical Analysis and Applied Mathematics 2009, Part 1, Rethymno, Crete (Greece), 18 – 22 September 2009. American Institute of Physics
  • S. Atslega and F. Sadyrbaev. Multiple solutions of the second order nonlinear Neumann BVP. Dynamics of Continuous, Discrete and Impulsive Systems (Series A). DCDIS A Supplement dedicated to the 6th International Conference on Differential Equations and Dynamical Systems held in Baltimore, U.S.A., May 22 - 26 - Watam Press, 2009, 100–103.
  • A. Gritsans, F. Sadyrbaev and N. Sergejeva. Two parameter nonlinear eigenvalue problems. Mathematical Models in Engineering, Biology, and Medicine, Proceedings of the International Conference on Boundary Value Problems, American Institute of Physics Conference Proceedings, 2009, V. 1124, 185-194. American Institute of Physics
  • S. Atslega and F. Sadyrbaev. Period annuli and multiple solutions for two-point BVP. Tatra Mountains Mathematical Publications, V. 43, 2009, 11–23. Link
  • I. Yermachenko and F. Sadyrbaev. Multiple solutions of nonlinear boundary value problems for two-dimensional differential systems. Dynamical Systems and Differential Equations.   Proc. of  the 7th AIMS International Conference (Arlington, TX, USA, 2008), DCDS Supplement 2009, 659 - 668. American Institute of Mathematical Sciences
  • F. Sadyrbaev and I. Yermachenko. Multiple solutions of two-point nonlinear boundary value problems. Nonlinear Analysis: TMA, V. 71, N. 12, 2009, e176 – e185, Proc. WCNA 2008, Orlando FL, USA, 2008. Elsevier
  • A. Gritsans and F. Sadyrbaev. Two-parametric nonlinear eigenvalue problems. E. J. Qualitative Theory of Diff. Equ., Proc. 8'th Coll. Qualitative Theory of Diff. Equ., N. 10, 2008, 1-14. EJQTDE
  • F. Sadyrbaev and I. Yermachenko. Types of solutions and multiplicity results for two-point nonlinear boundary value problems. Proceedings of AIMS' Sixth International Conference on Dyn. Systems, Diff. Equations and Applications University of Poitiers, Poitiers, France, June 25 - 28, 2006, Discrete and Continuous Dynamical Systems -  Supplement 2007, American Institute of Mathematical Sciences, 1061-1069. American Institute of Mathematical Sciences

  • F. Sadyrbaev and A. Gritsans. Nonlinear spectra for parameter dependent ordinary differential equations. Nonlinear Analysis: Modelling and Control, V. 12, N. 2, 2007, 253–267. LANA pdf
  • F. Sadyrbaev. Multiplicity of solutions for second order two-point boundary value problems with asymptotically asymmetric nonlinearities at resonance. Georgian Mathematical Journal, V. 14, N. 2, 2007, 351–360. De Gruyter
  • A. Gritsans and  F. Sadyrbaev. On the Nehari solutions. Proceedings of Equadiff 11, International Conference on Differential Equations. Czecho-Slovak series, Bratislava, July 25-29, 2005. [Part 2] Minisymposia and contributed talks. Comenius University Press, Bratislava, 2007, pp. 437-446. Czech Digital Mathematics Library
  • A. Gritsans and F. Sadyrbaev. Characteristic numbers of non-autonomous Emden-Fowler type equations. Mathematical Modelling and Analysis, V. 11, N. 3, 2006, p.243-252. Taylor & Francis pdf
  • F. Sadyrbaev and I. Yermachenko. Quasilinearization and multiple solutions of the Emden-Fowler type equation.  Mathematical Modelling Analysis, V. 10, N. 1, 2005, 41-50. Taylor & Francis
  • F. Sadyrbaev and I. Yermachenko. Types of solutions and multiplicity results for two-point non­linear boundary value problems. Nonlinear Analysis: TMA, V. 63, N. 5-7, 2005, e1725 – e1735. Elsevier
  • A. Gritsans and F. Sadyrbaev. Remarks on lemniscatic functions. Acta Universitatis Latviensis, V. 688. Mathematics, 2005, 39-50.  pdf dspace.lu.lv
  • A. Gritsans and F. Sadyrbaev. The Taylor series expansion coefficients for solutions of the Emden-Fowler type equations. Mathematical Modelling and Analysis, V. 10, N. 1, 2005, 247-256. Taylor & Francis pdf
  • F. Sadyrbaev. Nonlinear boundary value problems of the calculus of variations.  Discrete and Continuous Dynamical Systems - Supplement Volume,  American Institute of Mathematical Sciences, 2003, 770-779. American Institute of Mathematical Sciences
  • Yu. Klokov  and F. Sadyrbaev. Sharp conditions for rapid nonlinear oscillations. Nonlinear Analysis: TMA, V. 39, N. 39, 2000,  519–533. Elsevier
  • Yu. Klokov  and F. Sadyrbaev. Rapid oscillations in sublinear problems. Funkcialaj Ekvacioj,  V. 42, N. 3, 1999,  339–353. Link
  • M. Henrard and  F. Sadyrbaev. Multiplicity results for fourth-order two-point boundary value problems with asymmetric  nonlinearities. Nonlinear  Analysis: TMA, V. 33, N. 3, 1998, 281–302. Elsevier
  • F. Sadyrbaev. Multiplicity of solutions for two-point boundary value problems with asymptotically asymmetric nonlinearities, Nonlinear Analysis: TMA, V. 27, N. 9, 1996, 999-1012. Elsevier
  • F. Sadyrbaev. Nonlinear two-point fourth order  boundary value problems.  Rocky Mountain Journal of Mathematics, V. 25, N. 2, 1995, 757–781. Link

Recent Conferences and Invited Talks

 
 
  • International conference of numerical analysis and applied mathematics (ICNAAM2016), Rhodes, Greece, 2016   http://icnaam.org/
 
 
 
  • The 2015 International Conference on Simulation, Modelling and Mathematical Statistics, Chiang Mai, Thailand  http://www.smms2015.org/
 
 
 
  • The international conference "Actual problems of mathematics and mathematical modeling", dedicated to the 50th anniversary of the foundation of the Institute of Mathematics and Mathematical Modeling of Education and Science Ministry of the Republic of Kazakhstan,  in Almaty, 2015 http://www.math.kz/conf/index.php/en/

 
 
 
 
  • Symposium on Differential Equations and Difference Equations, Homburg/Saar, Germany, 2014
 
 
  • F. Sadyrbaev, A. Gritsans. On extension of Nehari-Moore example//Book of abstracts of Conference on Differential and Difference Equations and Applications, Jasná, Slovak Republic, June 23-27, 2014, P. 49. http://fpv.uniza.sk/cddea2014/
 
  • Symposium on Differential Equations and Difference Equations SDEDE 2013, Bayrischzell, Germany, 2013
 
 
  • International Conference on the Theory, Methods and Applications of Nonlinear Equations, Kingsville, USA, 2012 Link
 
  • Symposium on differential equations and difference equations, Novacella, Italy, 2012 Link
 
  • The Fifth International Workshop Constructive methods for non-linear boundary value problems, Tokaj, Hungary, 2012 Link
 
  • 7th European Conference on Elliptic and Parabolic Problems, Gaeta, Italy, 2012 Link
 
  • Equadiff, Loughborough University, GB, 2011 Link
 
  • International Conference on Differential & Difference Equations,Ponta Delgada, Portugal, 2011 Link
 
  • General Assembly of International Mathematical Union, Bangalore, India, 2010 Link
 
  • The 8th AIMS Conference on Dynamical Systems, Differential Equations and Applications, Dresden, Germany, 2010 Link
 
  • Emerging Problems in Nonlinear Analysis and Differential Equations: Advances in Theory and Applications, Glasgow, 2010 Link
 
  • Conference on Differential and Difference Equations and Applications 2010 (CDDEA 2010), Rajecke Teplice, Slovakia (invited lecturer and member of program committee) Link
 
  • 7th ISAAC Congress, Imperial College, London, 2009 Link
  • World Congress of Nonlinear Analysts 2008, FL, USA, July 2008, Orlando, FL, USA (invited lecturer in two special sessions) Link
 
  • Conference on Boundary Value Problems Mathematical Models In Engineering, Biology And Medicine, September 16-19, 2008, Santiago de Compostela, Spain (invited lecturer) Link
 
  • Conference on Differential and Difference Equations and Applications, Strečno, Slovak Republik, 2008 (invited lecturer and member of program committee) Link
  • The 6th International Conference On Differential Equations and Dynamical Systems, May 22-26, 2008, Baltimore, Maryland, USA Link
  • Amer. Inst. Math. Stud.  7th International Conference on Dyn. Systems, Diff. Equations and Applications, University of Texas at Arlington, Texas, USA May 18 - 21, 2008 Link
 
  • Equadiff-07, Vienna, Austria, 2007 Link
 
  • Amer. Inst. Math. Stud. 6th International Conference on Dyn. Systems, Diff. Equations and Applications, University of Poitiers, Poitiers, France, June 25 - 28, 2006 Link
 
  • The World Congress of Nonlinear Analysts 2004, FL, USA, July 2004, Orlando, FL, USA  (invited lecturer in two special sessions) Link

 
  • Equadiff-2003, July 22-26, 2003,  Hasselt, Belgium Link
 
  • International Congress of Mathematicians, Bejing, China, 2002 Link
 
  • Fourth International Conference on Dynamical Systems and Differential Equations,  May 24 - 27, 2002, Wilmington, NC, USA  (invited lecture)
Activities  
 
  • Member of the Latvian Mathematical Society
  • Member of the American Mathematical Society