Mittag-Leffler-type enclosures Riemann–Liouville integral SEIR epidemic model autonomous underwater vehicle bounded uncertainties collocation method direct autotuning methods distributed interval observer error event triggered exponential enclosures finite difference method finite-time convergence fixed-point theory fractional calculus fractional differential systems fractional diffusion equation fractional fourier transform fractional integral equation fractional order fractional-order controllers fractional-order differential equations fractional-order multiagent systems frequency distributed exponential function fuzzy logic control generalized Caputo derivate indirect autotuning methods infectious diseases infinite-state approach initial value problem