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The concept of energy-regenerative damping is adopted in semi-active vortex-induced vibration (VIV) suppression of an elastically supported inclined impenetrable elliptical cylinder modeled as a two degree-of-freedom (DOF) system in laminar cross-flow at low Reynolds numbers (Re = 210). It is based on the intelligent (model free) adaptive fuzzy sliding mode control (AFSMC) strategy in conjunction with switch-based energy regenerating circuit of a tunable electromagnetic (EM) damper. The semi-active damper is linked to the plant model in a multi-field co-simulation framework via MATLAB/Simulink coupled with a user defined function in a CFD package. The AFSM controller initially calculates the desired transverse control force for suppression of the cylinder VIV. Consequently, by smart adjustment of the variable circuit load resistance, the current flow through EM damper circuit is adaptively modulated in such a way that the damping force continually tracks its active counterpart in a semi-active manner. Furthermore, when the damper is operating in the regeneration mode, the mechanical vibration energy that is traditionally dissipated as heat in conventional viscous dampers will be stored as electric charge in a capacitor. Numerical simulations demonstrate that the regenerative semi-active EM-based VIV control system can effectively suppress the cylinder motion while recovering a certain portion of mechanical vibration energy through the cooperative action of two distinct operation modes of the EM damper. Unlike conventional active control systems, the proposed system does not require a large external power supply, and at least part of the required power may be provided by the recovered energy.

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