No abstract

This work deals with the passive control of horseshoes chaos in dissipative nonlinear chemical oscillations which concentration dynamics are governed by a forced modified Van der Pol-Duffing oscillator. We considered the dynamics of nonlinear chemical systems subjected to fluctuating hydrodynamic drag forces. The influences of the such parameter of the control force on the depth of asymmetric double well potential are analyzed. The Melnikov method is utilized to analytically determine the domains boundaries where horseshoes chaos appears in chemical oscillations. The effects of the constraint parameter β and of the control parameters in the all directions of passive control force are analyzed. Results of analytical investigations are validated and complemented by numerical simulations for draw the fractal basin of attraction and the efficiency of the control force is discussed.

This work studies the active control of chemical oscillations governed by a forced modified Van der Pol-Duffing oscillator. We considered the dynamics of nonlinear chemical systems subjected to an external sinusoidal excitation. The approximative solution to the first order of the modified Van der Pol-Duffing oscillator is found using the Lindstedt's perturbation method. The harmonic balance method is used to find the amplitudes of the oscillatory states of the system under control. The effects of the constraint parameter and the control parameter of the model on the amplitude of oscillations are presented. The effects of the active control on the behaviors of the model are analyzed and it appears that with the appropriate selection of the coupling parameter, the chaotic behavior of the model has given way to periodic movements. Numerical simulations are used to validate and complete the analytical results obtained.

This work studies the determination of analytical solution and cycle limite in nonlinear chemical oscillations gouverned by a forced modified Van der Pol-Duffing oscillator. We considered the dynamic of nonlinear chemical systems subjected to an external sinusoidal excitation. The first order appoximative solution of the oxcillator is determined using the Lindstedt’sperturbation method. The limit cycle number of the oscillator is found as well as the effect of certain parameters of the model on cycle limit analyzes. The harmonic balance method is used to find the amplitudes of the oscillatory states. The effect of the constraint parameter β of the oscillator are observed on amplitude-response curves. Numerical simulations are used to validate the results obtained by analytical methods.

Abstract. This study assessed the extreme rainfall and temperature changes over Mono river basin by the end of 21st century under the highest greenhouse gas emission scenario RCP8.5. Simulations of eight regional climate models (RCMs) provided by Africa-CORDEX program were considered. The maximum and minimum temperatures and rainfall were analyzed. Two groups of indices were analyzed. The first group consists of frequency indices: maximum number of consecutive dry days and wet days. The second group is intensity indices: five-day maximum rainfall and simple daily intensity index. These variables were calculated at annual and seasonal scales. Changes from the baseline period 1971–2000 were computed for far future 2071–2100. As result, almost all the RCMs considered predicted a decrease of the rainfall and increase of maximum and minimum temperatures over most parts of the Mono basin, particularly in the south. Declining mean monthly precipitation and irregular rainy seasons at all scales were exhibited by most of the models. Simple daily intensity and five-day maximum rainfall are projected to decrease by the majority of the used models. As for dry and wet sequences, the RCMs showed an increase of the consecutive dry days and a decrease of wet days.