The responses of dynamical systems under random forcings is a well-understood area
of research. The main tool in this area, as it has evolved over a century, falls under
the heading of stochastic differential equations. Most works in the literature are
related to random forcings with a known parametric spectral density. This paper
considers a new framework: the Cauchy and Dagum covariance functions indexing the
random forcings do not have a closed form for the associated spectral density, while
allowing decoupling of the fractal dimension and Hurst effect. On the basis
of a first-order stochastic differential equation, we calculate the transient
second-order characteristics of the response under these two covariances and make
comparisons to responses under white, Ornstein–Uhlenbeck, and Matérn
noises.
Keywords
random dynamical system, stochastic ordinary differential
equation, fractal, Hurst effect