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System Disturbance (system + disturbance)

Distribution by Scientific Domains

Medical Sciences	50%
Engineering	50%

Selected Abstracts

Necrotizing Vasculitis: A Cause of Aortic Insufficiency and Conduction System Disturbance

ECHOCARDIOGRAPHY, Issue 7 2003
Miquel Gómez Pérez M.D.
Cardiac involvement in vasculitis syndromes is uncommon. We describe a 50-year-old male who presented with progressive dyspnea and myalgies. Echocardiogram revealed significant thickening of aortic root, aortic cusps, and anterior mitral valve leaflet, with severe aortic regurgitation that required aortic valve replacement. Furthermore, this patient suffered progressive atrioventricular block that needed implantation of a pacemaker. The study performed disclosed the presence of necrotizing vasculitis positive for perinuclear antineutrophil cytoplasmic antibody. (ECHOCARDIOGRAPHY, Volume 20, October 2003) [source]

Accident risks in disturbance recovery in an automated batch-production system

HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 4 2002
G. Toulouse
Accident risks in automated production systems occur mainly during system disturbance. However, few studies have dealt with this issue. We were able to investigate it by studying accident risks during the recovery of incidents occurring in the running of an automated bread production system in an industrial bakery. This problem was examined through worker interviews. The main results indicate that the accident risks associated with system disturbance are due to accessibility problems and the need to operate quickly to avoid production shutdowns or material damage. Different solutions have been implemented to reduce the disturbances and accident risks. The development of these solutions seems related to the managers' and operators' concepts of what constitutes a disturbance. © 2002 Wiley Periodicals, Inc. [source]

Vasopressin in the treatment of vasodilatory shock in children

PEDIATRICS INTERNATIONAL, Issue 2 2005
Satoshi Masutani
Abstract,Background:,Many recent studies suggest that vasopressin deficiency is an important cause of catecholamine-resistant hypotension with vasodilation in adults, but little is known about vasopressin deficiency in children. Methods:,To clarify the usefulness of vasopressin administration in pediatric cathecolamine-resistant hypotension with preserved ventricular contractility, urinary output and blood pressure response to vasopressin were retrospectively analyzed in 12 consecutive patients (15 instances) who were treated with vasopressin. The causes of vasodilation were central nervous system disturbance (n = 5), side-effect of drug (n = 5), and infection (n = 5). Plasma vasopressin concentration was measured six times before vasopressin administration and five times during vasopressin administration. Results:,Patients were divided into four groups according to their response to vasopressin administration. In group 1 (n = 5), urinary output increased to > 3 mL/kg per h within 3 h after vasopressin administration. In group 2 (n = 4), urinary output increased to > 3 mL/kg per h from 3 to 5 h after vasopressin administration. In group 3 (n = 4), urinary output did not increase to > 3 mL/kg per min within 5 h after vasopressin administration, but systolic blood pressure increased to > 120% of the level at the time of vasopressin administration. All remaining patients were classified into group 4 (n = 3). Plasma vasopressin concentration were low considering the markedly hypotensive state in all six instances. Plasma vasopressin concentration during vasopressin administration were significantly increased compared with before administration (P < 0.05). No apparent side-effects were observed in this series. Conclusion:,Vasopressin deficiency may occur in catecholamine-resistant hypotension of pediatric patients due to various causes including central nervous system disturbance, drug induced hypotension and sepsis. Small doses of vasopressin administration seems to be very effective in such conditions by increasing blood pressure and urinary output. [source]

On fusion of PCA and a physical model-based predictive control strategy for efficient load-cycling operation of a thermal power plant

OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 4 2007
Girijesh Prasad
Abstract Controlling a thermal power plant optimally during load-cycling operation is a very challenging control problem. The control complexity is enhanced further by the possibility of simultaneous occurrence of sensor malfunctions and a plethora of system disturbances. This paper proposes and evaluates the effectiveness of a sensor validation and reconstruction approach using principal component analysis (PCA) in conjunction with a physical plant model. For optimal control under severe operating conditions in the presence of possible sensor malfunctions, a predictive control strategy is devised by appropriate fusion of the PCA-based sensor validation and reconstruction approach and a constrained model predictive control (MPC) technique. As a case study, the control strategy is applied for thermal power plant control in the presence of a single sensor malfunction. In particular, it is applied to investigate the effectiveness and relative advantage of applying rate constraints on main steam temperature and heat-exchanger tube-wall temperature, so that faster load cycling operation is achieved without causing excessive thermal stresses in heat-exchanger tubes. In order to account for unstable and non-minimum phase boiler,turbine dynamics, the MPC technique applied is an infinite horizon non-linear physical model-based state-space MPC strategy, which guarantees asymptotic stability and feasibility in the presence of output and state constraints. Copyright © 2007 John Wiley & Sons, Ltd. [source]