309 research outputs found
Measurement Uncertainty within the Theory of Evidence
No full textThis monograph considers the evaluation and expression of measurement uncertainty within the mathematical framework of the Theory of Evidence. With a new perspective on the metrology science, the text paves the way for innovative applications in a wide range of areas. Building on Simona Salicone’s Measurement Uncertainty: An Approach via the Mathematical Theory of Evidence, the material covers further developments of the Random Fuzzy Variable (RFV) approach to uncertainty and provides a more robust mathematical and metrological background to the combination of measurement results that leads to a more effective RFV combination method. While the first part of the book introduces measurement uncertainty, the Theory of Evidence, and fuzzy sets, the following parts bring together these concepts and derive an effective methodology for the evaluation and expression of measurement uncertainty. A supplementary downloadable program allows the readers to interact with the proposed approach by generating and combining RFVs through custom measurement functions. With numerous examples of applications, this book provides a comprehensive treatment of the RFV approach to uncertainty that is suitable for any graduate student or researcher with interests in the measurement field.
The Ross-Yacoub Operation For Aneurismal Autograft Roots: A Strategy To Preserve Autologous Pulmonary Valves And Normal Quality Of Life
No full textAutograft dilatation is leading to an increase in root reoperations late after the Ross procedure. A 14-year clinical experience was reviewed to define the feasibility and outcome of the autograft valve-sparing root reoperation. METHODS: One hundred twenty-six patients surviving an average of 7.4 +/- 9.9 years after the Ross procedure underwent cross-sectional clinical and echocardiographic examination. Study end points were freedom from autograft dilatation (diameter >4 cm or 2.1 cm/m(2)), root reoperation, root replacement, and functional outcome after the valve-sparing reoperation. RESULTS: Thirty-one (25%) patients had dilatation, with 45% +/- 9% freedom at 14 years. In 14 (11%) patients an autograft aneurysm (>5.0 cm) was found: 12 had reoperations at 8.9 +/- 2.6 years after the Ross procedure. Risk factors for root reoperation at multivariate analysis were root technique (P = .01), root dilatation (P = .001), and follow-up duration (P = .06). Two patients had root replacement, and 10 (83%) had remodeling with valve preservation (8 Yacoub procedures and 2 sinotubular junction/ascending aorta procedures); all survived reoperation. Absence of severe autograft insufficiency (P = .04) and convergent-type aneurysm (P = .05) were associated with successful valve preservation. Fourteen-year freedom from root reoperation was 80% +/- 7%, and freedom from full root replacement was 97% +/- 4%. At 3.2 +/- 1.5 years (range, 0.2-4.8 years) after root reoperation, all patients are in New York Heart Association class I and are medication free: 9 of 10 patients have mild autograft valve insufficiency or less, and 1 required valve replacement 51 months after remodeling. One patient carried out 2 uncomplicated pregnancies 3 and 4 years after the Ross-Yacoub procedure. CONCLUSIONS: Root reoperation with pulmonary valve preservation is feasible in the majority of patients with autograft aneurysms, allowing for maintenance of normal quality of life. Referral of patients with a dilated root before the appearance of severe valve insufficiency increases the likelihood of pulmonary valve sparing. Functional behavior of remodeled autograft roots is rewarding; however, continued observation is warranted
Simplified model for evaluating ripple effects on commercial PEM Fuel Cell
No full textIn this paper a simple model for evaluating current ripple effects on commercial PEM fuel cells is presented. The model is formulated starting from the Randles equivalent circuit and extending it assuming a dielectric relaxation of the material to represent dynamic processes in the frequency range typical of inverter current ripple. The proposed equivalent circuit is experimentally validated on a 14 kW commercial Morphic PEM fuel cell at the frequencies of interest. Finally the effects of current ripple on the losses and fuel cell efficiency are discussed
Modello semplificato per la valutazione dell'effetto di ripple di corrente su una fuel cell commerciale
No full textLa crescente diffusione delle fuel cell ha fatto emergere negli ultimi anni problematiche di misura di particolare importanza in fase di caratterizzazione delle prestazioni della cella e identificazione di parametri di circuiti equivalenti. Questo articolo riaffronta il problema della valutazione degli effetti che il ripple di corrente introdotto dai convertitori di potenza può avere su una fuel cell, mettendo in evidenza i problemi di misura che si presentano nella caratterizzazione di questi effetti e le criticità associate all’utilizzo di circuiti equivalenti per l’interpretazione dei dati sperimentali
Spontaneous regression of a large rhabdomyoma of the interventricular septum.
No full textWe report the case of a large congenital rhabdomyoma of the interventricular septum diagnosed prenatally. The foetus was strictly monitored with ultrasound throughout the gestation period showing that the mass had increased in size until delivery. Despite the size of the mass, which appeared to occupy the right ventricle, the baby presented no symptoms both in utero and after birth. Serial echocardiography was used to document the regression of the mass in childhood
Simplified model for evaluating ripple effects on commercial PEM fuel cell
No full textIn this paper a simple model for evaluating current ripple effects on commercial PEM fuel cells is presented. The model is formulated starting from the Randles equivalent circuit and extending it assuming a dielectric relaxation of the material to represent dynamic processes in the frequency range typical of inverter current ripple. The proposed equivalent circuit is experimentally validated on a 14 kW commercial Morphic PEM fuel cell at the frequencies of interest. Finally the effects of current ripple on losses and fuel cell efficiency are discussed
A neonate with cyanosis and tortuous great arteries.
No full textsurgical repair of complex aortic arch disease in newbor
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