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Hamilton, Canada

Chen K.,280 Main Street West | Williams S.,University of Toronto | Chan A.K.C.,McMaster University | Mondal T.K.,McMaster University
Blood Coagulation and Fibrinolysis | Year: 2013

The management of cardiomyopathy in pediatric patients is complicated by the risk of cardiac-associated embolism. This review examines the incidence, risk factors, and treatment of embolism in dilated cardiomyopathy (DCM), restrictive cardiomyopathy (RCM), and noncompaction of the left ventricular myocardium (NLVM) in children. The reported incidence of embolism for DCM ranges from 1 to 16%. Left ventricular ejection fraction below 25% or fractional shortening below 15% are major risk factors for intracardiac thrombus formation in this group. The risk of embolism for RCM ranges from 12 to 33%. Atrial dilation is considered the major risk factor. The reported incidence of embolism for NLVM ranges from 0 to 38%, with most studies indicating an absence of detectable thrombus or embolus. Severe systolic dysfunction exacerbates the risk of embolism in this group. On the basis of these risk factors, we propose an algorithm for the management of embolism in these groups of patients. © 2013 Wolters Kluwer Health. Source

Du M.,280 Main Street West | Mhaskar P.,280 Main Street West
Automatica | Year: 2014

This work considers the problem of sensor fault isolation and fault-tolerant control for nonlinear systems subject to input constraints. The key idea is to design fault detection residuals and fault isolation logic by exploiting model-based sensor redundancy through a state observer. To this end, a high-gain observer is first presented, for which the convergence property is rigorously established, forming the basis of the residual design. A bank of residuals are then designed using a bank of observers, with each driven by a subset of measured outputs. A fault is isolated by checking which residuals breach their thresholds according to a logic rule. After the fault is isolated, the state estimate generated using measurements from the healthy sensors is used in closed-loop to maintain nominal operation. The implementation of the fault isolation and handling framework subject to uncertainty and measurement noise is illustrated using a chemical reactor example. © 2014 Elsevier Ltd. All rights reserved. Source

Du M.,280 Main Street West | Scott J.,280 Main Street West | Mhaskar P.,280 Main Street West
Chemical Engineering Science | Year: 2013

This work considers the problem of isolating actuator and sensor faults in nonlinear process systems. The key idea of the proposed method is to exploit the analytical redundancy in the system through state observer design. To this end, we consider subsets of faults, and design state observers that use information of inputs and outputs only subject to faults in each subset. We then design residuals using the process model and state estimates such that each residual is only sensitive to the corresponding subset of faults. The occurrence of faults in a subset is detected if the corresponding residual breaches its threshold. With the ability of detecting the occurrence of faults in a subset, faults can be isolated using a bank of residuals and a logic rule. The proposed method enables differentiation between and isolation of actuator and sensor faults while explicitly accounting for system nonlinearity. The effectiveness of the fault isolation design subject to plant-model mismatch and measurement noise is illustrated using a chemical reactor example. © 2013 Elsevier Ltd. Source

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