PSO optimized PID regulator for a variable frequency brushless synchronous generator

The aim of this paper is to describe development of a new control structure for Automatic Voltage Regulator system. This approach is based on the optimization of the control voltage magnitude of a brushless excitation synchronous alternator machine operating at variable speed. The choice of the machine type is justified by its attractiveness in several areas such as the aircraft domain due to its autonomy and robustness. The considered control technique is based on the simultaneous optimization of two regulators introduced in the loop control. The parameters of the Proportional Integral Derivatives (PID) regulator have been optimized using the Particle Swarm Optimization (PSO), which is considered as an attractive method considering the wide operating speed range, and the load variations compared with the classical methods such as Ziegler Nichols. Many robustness tests are carried out by considering the parameters variations as well as the perturbation connection and disconnection of the load at low and high speeds

Endovascular repair of abdominal aortic aneurysm reduces intraoperative cortisol and perioperative morbidity

Copyright © 2005 The Society for Vascular Surgery Published by Mosby, Inc.Background: The release of catabolic stress hormones because of surgical trauma leads to a breakdown of fats, proteins, and carbohydrate stores and interference with immune function. This can delay wound healing and may increase the risk of systemic inflammatory response syndrome (SIRS)/sepsis and postoperative complications. Minimally invasive surgery can attenuate this response. Our purpose was (1) to compare neuroendocrine responses in patients undergoing open abdominal aneurysm repair with those in patients undergoing endovascular aneurysm repair (EVAR), (2) to compare the incidence of SIRS/sepsis and all complications in these two groups, and (3) to look at the relationship between procedure type, neuroendocrine response, and incidence of SIRS/sepsis and complications. Methods: Forty-six patients who underwent open repair and 19 who underwent EVAR were studied. A baseline (T1) 24-hour urine save was undertaken in the week before admission, and a second 24-hour save (T2) commenced at anesthetic induction to measure cortisol and catecholamines. The incidences of SIRS/sepsis and complications were recorded. Results: Significant (P ≤ .001) increases in cortisol and adrenaline from T1 to T2 occurred in all patients. Controlling for the type of anesthetic, the administration of exogenous inotropes, and β-adrenoreceptor antagonists (β-blockers), there was a significant difference in cortisol (T2) associated with the type of procedure. Responses were greater in open patients in comparison to EVAR patients (F3,61 = 5.0; P = .03). The incidence of SIRS (50% vs 32%), sepsis (26% vs 5%), and all complications (76% vs 32%) was significantly (P ≤ .02) higher in open than EVAR patients, respectively. Cortisol and adrenaline measured for 24 hours, commencing at the time of induction, tended to be higher in patients with SIRS/sepsis and all complications, but this did not reach significance. Conclusions: An attenuated glucocorticoid surge characterizes the reduced stress response experienced by patients undergoing EVAR compared with open abdominal aortic aneurysm repair. A reduction in the occurrence of SIRS is a feature of a more favorable postoperative course after an endovascular approach.Sue Pearson, Tiffany Hassen, J. Ian Spark, John Cabot, Prue Cowled and Robert Fitridgehttp://www.elsevier.com/wps/find/journaldescription.cws_home/623152/description#descriptio