U E Vincent
Articles written in Pramana – Journal of Physics
Volume 52 Issue 6 June 1999 pp 631-645 Research Articles
Structural properties of undercooled liquid sodium and caesium
O Akinlade B R Ijaduola U E Vincent G A Adebayo
Extensive theoretical results for the temperature dependence of the static and dynamical structure of undercooled alkali metals using Na and Cs as examples are presented. The static structural properties are obtained from the HMSA integral equations using pair potentials derived from an accurate non-local pscudopotential. The dynamical properties obtained from viscoelastic theory are compared with experiments and the results of memory function formalism. The study indicates that collective density excitations are more dominant in the undercooled region than at their melting points, and that the dynamical properties of Na and Cs exhibit subtle differences in their gross features.
Volume 68 Issue 5 May 2007 pp 749-756 Research Articles
Synchronization and basin bifurcations in mutually coupled oscillators
U E Vincent A N Njah O Akinlade
Synchronization behaviour of two mutually coupled double-well Duffig oscillators exhibiting cross-well chaos is examined. Synchronization of the subsystems was observed for coupling strength $k > 0.4$. It is found that when the oscillators are operated in the regime for which two attractors coexist in phase space, basin bifurcation sequences occur leading to $n + 1$, $n \geq 2$ basins as the coupling is varied – a signature of Wada structure and final-state sensitivity. However, in the region of complete synchronization, the basins structure is identical with that of the single oscillators and retains its essential features including fractal basin boundaries.
Volume 73 Issue 6 December 2009 pp 1011-1022
Global chaos synchronization of coupled parametrically excited pendula
O I Olusola U E Vincent A N Njah
In this paper, we study the synchronization behaviour of two linearly coupled parametrically excited chaotic pendula. The stability of the synchronized state is examined using Lyapunov stability theory and linear matrix inequality (LMI); and some sufficient criteria for global asymptotic synchronization are derived from which an estimated critical coupling is determined. Numerical solutions are presented to verify the theoretical analysis. We also examined the transition to stable synchronous state and show that this corresponds to a boundary crisis of the chaotic attractor.
Volume 96, 2022
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