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Average Method (average + method)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Optimal and self-tuning fusion Kalman filters for discrete-time stochastic singular systems

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 10 2008
Shu-Li Sun
Abstract Based on the optimal fusion estimation algorithm weighted by scalars in the linear minimum variance sense, a distributed optimal fusion Kalman filter weighted by scalars is presented for discrete-time stochastic singular systems with multiple sensors and correlated noises. A cross-covariance matrix of filtering errors between any two sensors is derived. When the noise statistical information is unknown, a distributed identification approach is presented based on correlation functions and the weighted average method. Further, a distributed self-tuning fusion filter is given, which includes two stage fusions where the first-stage fusion is used to identify the noise covariance and the second-stage fusion is used to obtain the fusion state filter. A simulation verifies the effectiveness of the proposed algorithm. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Product selection in Internet business: a fuzzy approach

INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 3 2010
B. K. Mohanty
Abstract In this paper, we propose a methodology which helps customers buy products through the Internet. This procedure takes into account the customer's level of desire in the product attributes, which are normally fuzzy, or in linguistically defined terms. The concept of fuzzy number will be used to measure the degree of similarities of the available products to that of the customer's requirements. The degrees of similarities so obtained over all the attributes give rise to the fuzzy probabilities and hence the fuzzy expected values of availing a product on the Internet as per the customer's requirement. Attribute-wise the fuzzy expected values are compared with those of the available products on the Internet and the product that is closest to the customer's preference is selected as the best product. The multi-attribute weighted average method is used here to evaluate and hence to select the best product. [source]

Enhanced Predictive Power of Quantitative TWA during Routine Exercise Testing in the Finnish Cardiovascular Study

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2009
MIKKO MINKKINEN B.M.S.
Introduction: We examined whether quantification of T-wave alternans (TWA) enhances this parameter's capacity to evaluate the risk for total and cardiovascular mortality and sudden cardiac death (SCD). Methods and Results: The Finnish Cardiovascular Study (FINCAVAS) enrolled consecutive patients (n = 2,119; 1,342 men and 777 women) with a clinically indicated exercise test with bicycle ergometer. TWA (time domain-modified moving average method) was analyzed from precordial leads, and the results were grouped in increments of 10 ,V. Hazard ratios (HR) for total and cardiovascular mortality and SCD were estimated for preexercise, routine exercise, and postexercise stages. Cox regression analysis was performed. During follow-up of 47.1 ± 12.9 months (mean ± standard deviation [SD]), 126 patients died: 62 were cardiovascular deaths, and 33 of these deaths were sudden. During preexercise, TWA , 20 ,V predicted the risk for total and cardiovascular mortality (maximum HR >4.4 at 60 ,V, P < 0.02 for both). During exercise, HRs of total and cardiovascular mortality were significant when TWA measured ,50 ,V, with 90 ,V TWA yielding maximum HRs for total and cardiovascular death of 3.1 (P = 0.03) and 6.4 (P = 0.002), respectively. During postexercise, TWA ,60 ,V indicated risk for total and cardiovascular mortality, with maximum HR of 3.4 at 70 ,V (P = 0.01) for cardiovascular mortality. SCD was strongly predicted by TWA levels ,60 ,V during exercise, with maximum HR of 4.6 at 60 ,V (P = 0.002), but was not predicted during pre- or postexercise. Conclusion: Quantification of TWA enhances its capacity for determination of the risk for total and cardiovascular mortality and SCD in low-risk populations. Its prognostic power is superior during exercise compared to preexercise or postexercise. [source]

Microvolt T-Wave Alternans during Holter Monitoring in Children and Adolescents

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2010
Leonid Makarov M.D.
Background: Time-domain microvolt T-wave alternans (TWA) has been described as a noninvasive marker of sudden cardiac death in adults. The incidence of TWA in pediatric populations has not been defined well. The aim of the study was to determine peculiarities of TWA in children. Methods: We examined 68 healthy patients,newborns (20) and children in age group of 7,17 years (48),and 85 pediatric patients: ventricular premature beats,65; dilated cardiomyopathy (DCMP),2; long QT syndrome (LQTS),10; Brugada syndrome (BrS),5, catecholaminergic ventricular tachycardia (CVT),3. All underwent Holter monitoring (HM) with definition of the peak value of TWA by modified moving average method. Results: In healthy newborns, TWA was 32 ± 8 (12,55) ,V (HR 123,156 bmp). In healthy children (7,17 years) it was 30 ± 11 (10,l 55) ,V, (HR 64,132 bmp) without any differences between boys and girls. In all group of patients, TWA were significantly higher (P < 0.05) than in healthy. Circadian peak of TWA was found (90%) in a second part of day and at sleep (8%). Among them 60% (LQTS, BrS, and DCPM) had TWA > 55 ,V. Conclusion: Time-domain TWA during HM in children was independent of age, gender, and heart rate. In 94% healthy children, values of TWA do not exceed 55 ,V but 20,50% children with cardiac pathology had TWA more than 55 ,V. Night circadian type of TWA in diseases with risk of life-threatening arrhythmias associated with TWA was more than 55 ,V. Ann Noninvasive Electrocardiol 2010;15(2):138,144 [source]