University of Seville

About: University of Seville is a education organization based out in Seville, Andalucía, Spain. It is known for research contribution in the topics: Population & Context (language use). The organization has 20098 authors who have published 47317 publications receiving 947007 citations. The organization is also known as: Universidad de Sevilla.

On the stability of constrained MPC without terminal constraint

Abstract: The usual way to guarantee stability of model predictive control (MPC) strategies is based on a terminal cost function and a terminal constraint region. This note analyzes the stability of MPC when the terminal constraint is removed. This is particularly interesting when the system is unconstrained on the state. In this case, the computational burden of the optimization problem does not have to be increased by introducing terminal state constraints due to stabilizing reasons. A region in which the terminal constraint can be removed from the optimization problem is characterized depending on some of the design parameters of MPC. This region is a domain of attraction of the MPC without terminal constraint. Based on this result, it is proved that weighting the terminal cost, this domain of attraction of the MPC controller without terminal constraint is enlarged reaching (practically) the same domain of attraction of the MPC with terminal constraint; moreover, a practical procedure to calculate the stabilizing weighting factor for a given initial state is shown. Finally, these results are extended to the case of suboptimal solutions and an asymptotically stabilizing suboptimal controller without terminal constraint is presented.

A brief survey of pineal gland-immune system interrelationships.

Abstract: The present paper summarizes evidence that support the hypothesis of the existence of bilateral interactions between pineal gland and the immune system. Both in vivo and in vitro experiments show that the pineal gland, via its hormone melatonin, enhances immune function. Mechanisms involved in this immunostimulatory effect are not well understood, but some evidence suggests the existence of specific binding sites for melatonin on immune cells. Moreover, the release of opioid peptides and interleukin-2 by T-helper cells may also participate in this mechanism by activating, at least natural killer activity and antibody-dependent cellular cytotoxicity. Some immune signals, i.e., gamma-interferon, may be involved in regulating pineal function, thereby representing a regulatory mechanism in the opposite direction. The physiological and clinical significance of these data remains to be studied.