A Comparison among Portfolio Selection Strategies with Subordinated Lévy Processes

In this paper we describe portfolio selection models using Lévy processes. The contribution consists in comparing some portfolio selection strategies under different distributional assumptions. We first implement portfolio models under the hypothesis the log-returns follow a particular process with independent and stationary increments. Then we compare the ex-post final wealth of optimal portfolio selection models with subordinated Lévy processes when limited short sales and transaction costs are allowed

Vibration control of wind turbines with variable rotor sped and grid faults

THESIS 10738The aim of this thesis is to propose, design and analyze vibration mitigation systems in wind turbines. Formulations have been developed to include variations of the rotational speed of the blades. The control methodologies to tackle the issue of structural vibrations in wind turbines are proposed and appropriate simulation tools are developed. Particular attention is given to the case in which changes of the rotor speed are induced by an imbalance of the generator torque due to an electrical grid fault. Numerical investigations have been carried out to ascertain the effectiveness of the proposed approaches in improving the dynamic response of wind turbines