Narrow Results

In this paper, we consider an environmental interface as a complex system, in which difference equations for calculating the environmental interface temperature and deeper soil layer temperature are represented by the coupled maps. First equation has its background in the energy balance equation while the second one in the prognostic equation for deeper soil layer temperature, commonly used in land surface parametrization schemes. Nonlinear dynamical consideration of this coupled system includes: (i) examination of period one fixed point and (ii) bifurcation analysis. Focusing part of analysis is calculation of the Lyapunov exponent for a specific range of values of system parameters and discussion about domain of stability for this coupled system. Finally, we calculate Kolmogorov complexity of time series generated from the coupled system.

Two methodologies are presented for the numerical approximation of the "domain of stability" of nonlinear conservative maps: (a) the Evolutionary Estimation of the Domain of Stability (EEDS) and (b) the Evolutionary Frequency Optimization (EFO), optimizing certain frequency parameters of these maps so that the domain of stability encompasses the maximum possible "volume" of bounded motion, known in the accelerator literature as the dynamic aperture. The central components of the proposed approaches are: The Differential Evolution algorithm (DE) based on concepts of Computational Intelligence and the method of the Smaller ALignment Index (SALI) used for the determination of chaotic dynamics. Initially, we give a brief description of the two methodologies and then demonstrate their usefulness by applying them to some well-known examples of 2D and 4D Hénon maps. The proposed methodologies can be easily applied to "volume" preserving maps which are not necessarily symplectic as well as to continuous dynamical systems (flows) and can also be generalized to treat conservative dynamical systems of any dimension.

In this paper, a Lyapunov function is generated to determine the domain of asymptotic stability of a system of three first order nonlinear ordinary differential equations describing the behaviour of a nuclear spin generator (NSG). The generated Lyapunov function, is a simple quadratic form, whose coefficients are chosen so that the Routh-Hurwitz criteria are satisfied for the corresponding linear differential equations.