About me

Research interests

  1. Integral equations, operator semigroups, duality, and perturbation theory
  2. Existence, stability, and bifurcation of parameter-dependent equilibria and periodic orbits
  3. Time delay effects in systems and control

For my work on the above I am kindly hosted by Utrecht University, The Netherlands.
My PhD advisers are O. Diekmann and S.M. Verduyn Lunel.

Contact information

You can contact me via email (can be used with my PGP key) or more email.
I have a profile on ResearchGate.

Pre-prints and publications

S.G. Janssens, A class of abstract delay differential equations in the light of suns and stars. Part II, March 2020, arXiv:2003.13341 [math.DS, math.FA].
Presentation video and slides about this work for the third installment of the Delay Days, online, 1 October 2020.

M.M. Bosschaert, S.G. Janssens, Yu.A. Kuznetsov, Switching to nonhyperbolic cycles from codimension two bifurcations of equilibria of delay differential equations, March 2019, arXiv:1903.08276 [math.DS]. Accepted for publication in SIAM Journal on Applied Dynamical Systems.

S.G. Janssens, A class of abstract delay differential equations in the light of suns and stars. Part I, January 2019, arXiv:1901.11526 [math.DS, math.FA].
Presentation about this work for a day on Delay equations, theory and applications, Utrecht, 15 February 2019.

K. Dijkstra, S.A. van Gils, S.G. Janssens, Yu.A. Kuznetsov, S. Visser, Pitchfork-Hopf bifurcations in 1D neural field models with transmission delays, Phys. D 297 (2015), 88–101, DOI: 10.1016/j.physd.2015.01.004.

S.A. van Gils, S.G. Janssens, Yu.A. Kuznetsov, S. Visser, On local bifurcations in neural field models with transmission delays, J. Math. Biol. 66 (2013), no. 4-5, 837–887, DOI:10.1007/s00285-012-0598-6 and arXiv:1209.2849 [math.DS].

S.G. Janssens, On a Normalization Technique for Codimension Two Bifurcations of Equilibria of Delay Differential Equations, Master Thesis, Utrecht University, 2010, original or with updates (latest: 20 November 2018).

My master thesis was written under supervision of Yu.A. Kuznetsov with Odo Diekmann as co-supervisor. The updated version contains corrections and some new material – see the Summary of updates and corrections. It is available under a Creative Commons BY-NC-ND 4.0 International license.

Site credits

I am a grateful user of various high quality programs that are part of the GNU project.