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SCI-SSCI or SCI Expanded Articles

  • S. Hakkav, Spectral stability of periodic waves for the Drinfeld-Sokolov-Wılson equation, Journal of Mathematical Analysis and Applications, 533(1)(2024), 128016
  • S. Hakkaev, M. Stanislavova, A. Stefanov, Spectral stability of periodic waves for the Zakharov system, Journal of Mathematical Physics, 64(8)(2023), 081503
  • S. Hakkaev, T. Syuleymanov, On the linear stability of simple and semi-simple periodic waves for a system of cubic Klein-Gordon equations, Mathematische Nachrichten, 296(5)(2023), 1886-1900
  • S. Hakkaev, M. Stanislavova, A. Stefanov, On the Stability of the Periodic Waves for the Benney System, SIAM Journal on Applied Dynamical Systems, 21(3)(2022), 1726-1747
  • S. Hakkaev. A. Ramadan, A. Stefanov, “On the stability of the compacton waves for the degenerate KdV and NLS models”, Quarterly of Applied Mathematics, 80(3)(2022), 507-528
  • S. Hakkaev, F. Hunutlu, “Linear stability of periodic standing waves of the KGZ system”, Turkish Journal of Mathematics, 45(6)(2021), 2594-2602
  • S. Hakkaev, M. Stanislavova, A. Stefanov, “On the stability of periodic waves for the cubic derivative NLS and the quintic NLS”, Journal of Nonlinear Science, 31(2021), No 54, pp. 38
  • S. Hakkaev, A. Stefanov, Stability of periodic traveling waves for the fractional KdV and NLS equations, Proceedings of the Royal Society of Edinburgh: Section A Mathematics, 151(4)(2021), 1171-1203
  • S. Hakkaev, Orbital stability and instability of solitary waves for a class of dispersive symmetric regularized long wave equation, Mediterranean Journal of Mathematics , 16(4)(2019), 92
  • S. Hakkaev, Stability of semitrivial periodic waves of a Schrodinger system, Journal of Mathematical Physics, 60(2019), 081502 (12 pp)
  • S. Hakkaev, M. Stanislavova, A. Stefanov, On the generation of stable Kerr frequency combs in the Lugiato-Lefever model of periodic optical waveguides, SIAM Journal on Applied Mathematics, 79(2) (2019), 477-505
  • S. Hakkaev. M. Stanislavova, A. Stefanov, “Spectral stability for classical periodic waves of the Ostrovsky and short pulse models”, Studies in Applied Mathematics, 139(3)(2017), 405-433
  • S. Hakkaev. M. Stanislavova, A. Stefanov, Periodic travelling waves of the regularized short pulse and Ostrovsky equations: existence and stability, SIAM Journal on Mathematical Analysis, 49(1)(2017), 674-698
  • V. Hasanov, S. Hakkaev, Convergence analysis of some iterative method for a nonlinear matrix equation, Computers&Mathematics with Applications, 72(4)(2016), 1164-1176
  • V. Hasanov, S. Hakkaev, Newtons method for a nonlinear matrix equation, Comptes rendus de lAcademie bulgare des Sciences, 68(8) (2015), 973-982
  • A. Demirkaya, S. Hakkaev, “On the spectral stability of periodic waves for the coupled Schrodinger equations”, Physics Letters A, 379 (2015), 2908-2914
  • A. Demirkaya, S. Hakkaev, M. Stanislavova, A. Stefanov, “On the spectral stability of periodic waves of the Klein-Gordon equation”, Differential and Integral Equations, 28(5&6)(2015), 431-454
  • S. Hakkaev, “On the stability of periodic waves of the nonlinear wave system”, Compt. rend. Acad. bulg. Sci., 68(3)(2015), 305-312
  • S. Hakkaev, M. Stanislavova, A. Stefanov, “Linear stability analysis for periodic traveling waves of the Boussinesq equation and the KGZ system”, Proceedings of the Royal Society of Edinburgh: Section A Mathematics, 144(03) (2014), 455-489
  • S. Hakkaev, M. Stanislavova, A. Stefanov, “Spectral stability for subsonic traveling pulses of the Boussinesq ‘abc’ system, SIAM Journal on Applied Dynamical Systems, 12(2)(2013), 878-898
  • S. Hakkaev, I. Iliev, K. Kirchev “Stability of periodic traveling waves for the quadratic and cubic nonlinear Schrodinger equations”, International Journal of Bifurcation and Chaos, 23(5)(2013), 1350090 (20pp.)
  • S. Hakkaev, M. Stanislavova, A. Stefanov, “Orbital stability for periodic standing waves for the Klein-Gordon-Zakharov system and the beam equation”, Zeitschrift fuer Angewandte Mathematik und Physik, 64(2) (2013), 265-282
  • S. Hakkaev. M. Stanislavova, A. Stefanov, “Transverse instability for periodic traveling waves of KP-I and Schrodinger equations”, Indiana University Mathematics Journal, 61(2)(2012), 461-492
  • O. Christov, S. Hakkaev, I. Iliev, “Non-uniform continuity of periodic Holm-Staley b-family of equations”, Nonlinear Analysis, 75 (2012), 4821-4838
  • J. Jiang, S. Hakkaev, “Wave breaking and propagation speed for a class of one-dimensional shallow water equations”, Abstract and Applied Analysis, ID 647468 (2011), 15 pp.
  • 17. J. Angulo, A. Corcho, S. Hakkaev, “Well-posedness and stability in the periodic case for the Benney system”, Advances in Differential Equations, 16(2011), 523-550
  • J. Angulo, S. Hakkaev, “Ill-posedness for periodic nonlinear dispersive equations” , Electronic Journal of Differential Equations, 119(2010), 1-19
  • S. Hakkaev, I. Iliev, K. Kirchev, “Stability of periodic traveling waves for the complex modified Korteweg-de Vries Equation”, Journal of Differential Equations, 248(10)(2010), 2608-2627
  • O. Christov, S. Hakkaev, “On the Cauchy problem for the periodic b-family of equations and of the non-uniform continuity of Degasperis-Procesi equation” , Journal of Mathematical Analysis and Applications, 360(2009), 47-56
  • O. Christov, S. Hakkaev, “On the inverse scattering approach and action-angle variables for the Dullin-Gottwald-Holm equation”, Physica D, 238(2009), 9-19
  • S. Hakkaev, I. Iliev, K. Kirchev, “Stability of periodic traveling shallow water waves determined by Newton’s equation”, Journal of Physics A: Mathematical and Theoretical, 41(2008), no.8, 085203, 31p.(an article chosen for IOP Select)
  • . Hakkaev, “Orbital stability of solitary waves of the Schrodinger-Boussinesq equation”, Commun. Pure Applied Analysis, 6(4) (2007), 1043-1050
  • S. Hakkaev, K. Kirchev , “Stability of solitary wave solutions of nonlinear dispersive system in a critical case”, Nonlinear Analysis TMA, 57(2007), 2890-2899
  • S. Hakkaev, “Stability of peakons for an integrable shallow water equation”, Physics Letters A, 354(2006), 137-144
  • S. Hakkaev, K. Kirchev , “Local well-posedness and orbital stability of solitary wave solutions for the generalized Camassa-Holm equation”, Communications in Partial Differential Equations, 30(2005), 761-781
  • S. Hakkaev, K. Şamdanlı, On the spectral stability of periodic waves of the dispersive system of modified KdV equations, Nonlinear Analysis:RWA, 82(2025), 104250

International Articles

  • S. Hakkaev, “Linear stability analysis for periodic standing waves of the Klein-Gordon equation”, Differential Equations and Dynamical Systems, 22(2) (2014), 209-219
  • S. Hakkaev, “Nonlinear stability of periodic traveling waves of the BBM system”, Communications in Mathematical Analysis, 15(2)(2013), 39-51
  • S. Hakkaev, K. Kirchev , “On the well-posedness and stability of peakons for a generalized Camassa-Holm equation” , International Journal of Nonlinear Science, 3(2006), 139-148
  • S. Hakkaev, “Scattering of small solutions of symmetric regularized-long-wave equation”, Applications Math. (Warsaw) 31(2004), 313-320
  • S. Hakkaev, “Stability and instability of solitary wave solutions of a nonlinear dispersive system of Benjamin-Bona-Mahony type”, Serdica Math.J. 29(2003), 337-354
  • S. Hakkaev, Zh.Zhelev, R.Nickolov “Subscalarity of a class of operators”, Mathematica Balcanika, 17 (2003), 231-238
  • S. Hakkaev, K. Kirchev ,“Positivity properties and stability of solitary waves of Benjamin-Bona-Mahony type”, Compt. rend. Acad. bulg. Sci., 2001, T.55, No 7, 5-10
  • S. Hakkaev, K. Kirchev, “Stability and instability of traveling waves solutions of complex Benjamin-Bona-Mahony type”, Compt. rend. Acad. bulg. Sci.,2001, T.55,No 6, 17-22